                FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

VICTOR ANTONIO PARSONS; SHAWN              No. 13-16396
JENSEN; STEVE SWARTZ; DUSTIN
BRISLAN; SONIA RODRIGUEZ;                     D.C. No.
CHRISTINA VERDUZCO; JACKIE                 2:12-cv-00601-
THOMAS; JEREMY SMITH; ROBERT                   NVW
CARRASCO GAMEZ, JR.; MARYANNE
CHISHOLM; DESIREE LICCI; JOSEPH
HEFNER; JOSHUA POLSON;                       OPINION
CHARLOTTE WELLS; ARIZONA
CENTER FOR DISABILITY LAW,
               Plaintiffs-Appellees,

                 v.

CHARLES L. RYAN; RICHARD PRATT,
            Defendants-Appellants.

      Appeal from the United States District Court
               for the District of Arizona
        Neil V. Wake, District Judge, Presiding

              Argued and Submitted
     November 6, 2013—San Francisco, California

                      Filed June 5, 2014

    Before: Stephen Reinhardt, John T. Noonan, and
            Paul J. Watford, Circuit Judges.

              Opinion by Judge Reinhardt
2                        PARSONS V. RYAN

                           SUMMARY*


              Prisoner Civil Rights/Class Action

    The panel affirmed the district court’s order certifying a
class and a subclass of inmates in Arizona’s prison system
who alleged that they were subjected to systemic Eighth
Amendment violations.

    The panel held that the district court acted well within its
broad discretion in concluding that the putative class of
inmates challenging Arizona Department of Corrections’
health care policies and practices and the subclass of inmates
challenging the isolation unit polices and practices satisfied
the requirements for class certification set forth in Federal
Rule of Civil Procedure 23.

    The panel held that certification of the class and subclass
was appropriate with respect to Rule 23(a)(2)’s requirement
of commonality because plaintiffs’ claims set forth common
contentions whose truth or falsity could be determined in one
stroke: whether the specified statewide policies and practices
exposed them to a substantial risk of harm.

    The panel also held that the district court did not abuse its
discretion in determining that the named plaintiffs, inmates in
Arizona custody who alleged that they were exposed to a
substantial risk of harm by the challenged polices and
practices, satisfied the typicality requirement of Rule
23(a)(3).

  *
    This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
                      PARSONS V. RYAN                           3

    The panel held that considering the nature and contours
of the relief sought by the plaintiffs, the district court did not
abuse its discretion in concluding that a single injunction and
declaratory judgment could provide relief to each member of
the proposed class and subclass and therefore that plaintiffs
satisfied Rule 23(b)(2).


                          COUNSEL

Nicholas D. Acedo (argued) and Daniel P. Struck, Struck
Wieneke & Love, P.L.C., Chandler, Arizona; Thomas C.
Horne, Arizona Attorney General, and Michael E. Gottfried,
Assistant Attorney General, Phoenix, Arizona, for
Defendants-Appellants.

David C. Fathi (argued), ACLU National Prison Project,
Washington, D.C.; Daniel Pochada, ACLU Foundation of
Arizona, Phoenix, Arizona; Daniel C. Barr, Amelia M.
Gerlicher, Kirstin T. Eidenbach, Perkins Coie LLP, Phoenix,
Arizona; Caroline Mitchell, Jones Day, San Francisco,
California; Donald Specter and Corene Kendrick, Prison Law
Office, Berkeley, California; John Laurens Wilkes, Jones
Day, Houston, Texas; Jennifer K. Messina, Jones Day, New
York, New York, for Plaintiffs-Appellees.

Catherine Weiss, Michael Hahn, Jason Halper, and Monica
Perrette, Lowenstein Sandler LLP, Roseland, New Jersey;
Mark A. Chavez, Chavez & Gertler LLP, Mill Valley,
California, for Amici Curiae American Friends Service
Committee, Center for Children’s Law and Policy, Children’s
Rights, Impact Fund, National Alliance on Mental Illness
(NAMI), NAMI-Arizona, National Center for Youth Law,
National Disability Rights Network, National Immigrant
4                     PARSONS V. RYAN

Justice Center, National Juvenile Defender Center, Pacific
Juvenile Defender Center, The ARC of the United States, and
Youth Law Center.


                          OPINION

REINHARDT, Circuit Judge:

    The defendants, senior officials of the Arizona
Department of Corrections (“ADC”), appeal an order
certifying a class and a subclass of inmates in Arizona’s
prison system who claim that they are subject to systemic
Eighth Amendment violations. The inmates allege that
numerous policies and practices of statewide application
governing medical care, dental care, mental health care, and
conditions of confinement in isolation cells expose them to a
substantial risk of serious harm to which the defendants are
deliberately indifferent. The inmates seek declaratory and
injunctive relief from the alleged constitutional violations.
After reviewing the substantial record compiled by the
plaintiffs, which includes four expert reports, hundreds of
internal ADC documents, depositions of ADC staff, and
inmate declarations, the district court determined that the
plaintiffs meet the standard for class certification set forth in
Federal Rule of Civil Procedure 23. It therefore certified a
class of inmates challenging ADC health care policies and
practices, and a subclass of inmates challenging ADC
isolation unit policies and practices. We conclude that the
district court did not abuse its discretion in certifying the
class and subclass, and therefore affirm the order of the
district court.
                         PARSONS V. RYAN                                5

                         BACKGROUND

                                    I

     Arizona law requires the Director of the ADC to “provide
medical and health services” for the approximately 33,000
inmates in ten prison facilities who depend on the state for all
basic needs.1 Ariz. Rev. Stat. Ann. § 31-201.01; see also id.
at § 41-1604 (providing that “the director shall be responsible
for the overall operations and policies for the department”).
To satisfy the duty imposed by statute on its director, ADC
has promulgated extensive statewide policies governing
health care and conditions of confinement that apply to all of
the inmates in its custody, all of its staff, and all of its
facilities.2

    Since July 2012, ADC has contracted with private entities
to provide medical, dental, and mental-health care services to
inmates. Specifically, ADC hired Wexford Health Services
from July 1, 2012 through March 3, 2013, at which point it
replaced Wexford with Corizon, Inc., its current partner.
ADC’s private contractors are required by the plain terms of
their agreements to follow all ADC policies, and work with
ADC to implement additional policies governing such matters
as health care staffing, access to prescriptions, emergency
care, and dental care. The contractors’ full compliance with



   1
     Defendant Charles Ryan is the Director of ADC and Defendant
Richard Pratt is ADC’s former Interim Division Director of Health
Services. Ryan and Pratt have both been sued in their official capacities.
    2
      The ten ADC facilities are Douglas, Eyman, Florence, Lewis,
Perryville, Phoenix, Safford/Ft. Grant, Tucson, Winslow, and Yuma.
6                          PARSONS V. RYAN

statewide ADC policy is constantly monitored by ADC
officials.

    The plaintiffs are thirteen inmates in ADC custody and
the Arizona Center for Disability Law, Arizona’s authorized
protection and advocacy agency. See 42 U.S.C. § 10801.
They filed this suit in March 2012, claiming that ADC’s
policies and practices governing medical care, dental care,
and mental health care expose all inmates “to a substantial
risk of serious harm, including unnecessary pain and
suffering, preventable injury, amputation, disfigurement, and
death.” The plaintiffs support these general allegations with
detailed references to nearly a dozen specific ADC policies
and practices, including inadequate staffing, outright denials
of care, lack of emergency treatment, failure to stock and
provide critical medication, grossly substandard dental care,
and failure to provide therapy and psychiatric medication to
mentally ill inmates.

    The plaintiffs also claim that conditions in ADC isolation
units constitute cruel and unusual punishment.3 They allege,
for example, that prisoners in isolation often go months or
years without any meaningful interaction with other persons,
that these inmates are frequently denied adequate nutrition,
that some receive no outdoor exercise at all for months or
years on end, and that most inmates held in isolation are
confined to cells with 24-hour-a-day illumination. The
plaintiffs add that “[t]he predictable outcomes of these cruel


    3
   The plaintiffs and the district court use the term “isolation cells,” while
the defendants refer to the same cells as “maximum custody cells.”
Although we adopt the district court’s terminology, that decision does not
amount to an opinion about the substance of the plaintiffs’ conditions of
confinement claims relating to the isolation cells.
                      PARSONS V. RYAN                         7

conditions of isolation are psychiatric deterioration, self-
injury, and death.”

    With respect to both the health care and isolation unit
claims, the plaintiffs allege that ADC is aware of these
constitutionally defective conditions and has deliberately
ignored the resulting risk to which it has exposed inmates.
For example, the plaintiffs allege that, in 2009, the ADC
Director of Medical Services responded to a prison
physician’s complaint that ADC was failing to provide
adequate care by agreeing that ADC was “probably” violating
inmates’ rights and stating that “I do think that there would be
numerous experts in the field that would opine that deliberate
indifference has occurred.”

    The plaintiffs seek declaratory and injunctive relief to
eliminate identified systemic deficiencies in ADC’s statewide
health care system and isolation units.

                              II

    After the district court denied a motion to dismiss, the
plaintiffs moved for class certification. They supported their
motion with the detailed factual allegations in the Complaint,
hundreds of documents that they had obtained from the
defendants in discovery, expert reports by four specialists in
prison medical care and conditions of confinement, and
declarations by the named plaintiffs. The discovery materials
included assessments of ADC staffing, reports by contractor
monitors, internal communications between ADC officials,
and letters exchanged between ADC and Wexford. In their
response, the defendants relied on a few declarations by some
ADC officials in which those officials summarized formal
ADC policies—several of which had been modified mere
8                        PARSONS V. RYAN

days before the defendants filed their brief in the district
court. The defendants did not submit rebuttal expert
declarations, nor did they offer evidence that the newly
revised written statements of ADC policy reflected the actual
policy and practice of the ADC facilities. Further, the
defendants did not address the individual policies and
practices complained of by the plaintiffs nor present evidence
meant to deny their existence. Rather, the defendants argued
in a general fashion that ADC written policies are the only
statewide policies and practices.4

        A. Factual Allegations in the Complaint

    The 74-page complaint in this case contains detailed
factual allegations concerning the existence of uniform,
statewide policies and practices in all ADC facilities. In the
plaintiffs’ view, these policies and practices expose all ADC
inmates to a substantial risk of harm. With respect to their
health care claims, the plaintiffs allege the existence of the
following policies and practices: (1) creation of “lengthy and
dangerous delays in receiving” care and “outright denials of
health care”; (2) failure to “provide prisoners with timely
emergency treatment”; (3) failure to “provide necessary
medication and medical devices to prisoners”; (4) a practice
of “employ[ing] insufficient health care staff”; (5) failure to
“provide prisoners with care for chronic diseases and
protection from infectious diseases”; (6) failure to “provide
timely access to medically necessary specialty care”; (7)
provision of “substandard dental care”; (8) provision of
“substandard mental health care”; (9) denial of “medically


    4
    Of course, this argument is ineffective as to the several policies and
practices complained of by the plaintiffs that reflect formal ADC written
policy.
                      PARSONS V. RYAN                           9

necessary mental health treatment,” including “psychotropic
medication, therapy, and inpatient treatment,” to mentally ill
prisoners; and (10) denial of “basic mental health care” to
“suicidal and self-harming prisoners.” With respect to the
isolation units claims, the plaintiffs allege the existence of the
following policies and practices: (1) denial of adequate
recreation; (2) constant cell illumination; (3) extreme social
isolation; (4) denial of adequate nutrition; and (5) failure to
provide adequate mental health care staffing and treatment.

    For each of these alleged policies and practices, the
Complaint contains several paragraphs or pages of
particularized factual allegations. For example, with regard
to the alleged policy and practice of failing to provide
necessary medication and medical devices, the Complaint
alleges that the “[d]efendants have a policy and practice of
not providing prisoners with the full course of their
medication, not providing prisoners medication as prescribed
or in a timely fashion, and inappropriately starting and
stopping medication.” The Complaint further alleges that
“psychotropic medications that are to be taken daily regularly
go undelivered, without explanation or warning,” prisoners
“are given expired medication or incorrect dosages of
medication,” the defendants “routinely substitute doctor-
approved drug regimens with drugs on the ADC-approved
formulary,” and the defendants fail to provide “medically
necessary devices, thus depriving . . . prisoners of basic
sanitation.” The Complaint also includes factual allegations
that demonstrate the kinds of serious harm to which members
10                         PARSONS V. RYAN

of the proposed class are exposed by ADC policies and
practices.5

    To take another example of the medical care claims, the
Complaint alleges the existence of a policy and practice of
“failing to provide prisoners with specialty care, or doing so
only after extensive and unreasonable delays, often resulting
in unnecessary pain and suffering, permanent injuries, and
death.” The Complaint further alleges that, even though
ADC sends prisoners to contracted outside specialists, “[f]or
much of 2009 and 2010, Defendants had no contracts in place
with outside providers, and even today have few outside
specialists under contract to treat ADC prisoners.” The


  5
     Thus, with respect to the policy and practice of failing to provide
prisoners with necessary medication and medical devices, the Complaint
alleges the following examples, among others:

      •   “A prisoner at the Tucson complex was given the incorrect
          dosage of medication to treat his seizures in September 2011. He
          suffered a stroke, and despite pleas for help from his fellow
          inmates, waited more than a day before medical staff saw him
          and referred him to an outside hospital’s Intensive Care Unit.
          Now, due to the stroke, he slurs his speech, has difficulty
          walking and relies on a wheelchair, and is incontinent.”

      •   “When [a named plaintiff] [suffered an] eye injury, a nurse at the
          Safford prison gave him eye medication that had expired more
          than three months previously. When he used the medication, his
          vision dramatically worsened, and he developed iritis.”

      •   “[A named plaintiff] and other prisoners who need catheters are
          given fewer clean catheters than they need, and thus have to re-
          use the catheters, putting them at risk of bladder and urinary tract
          infections . . . Prisoners who need incontinence briefs or wipes
          often go without them, or are told they only are allowed one
          diaper per day.”
                          PARSONS V. RYAN                               11

Complaint elaborates that from FY 2009 to FY 2011,
“spending on specialty services had plummeted by 38% . . .
while there was no corresponding decline in the number of
prisoners in ADC’s custody.” The Complaint quotes ADC
physicians who stated that “the referral system has broken
down” and that specialist referrals are “falling through the
cracks,” and alleges that the defendants “have a policy and
practice of failing to order or approve outside diagnostic
testing, including biopsies of suspicious tumors and
growths.”6


 6
  The plaintiffs’ examples of the kinds of serious harm to which they are
exposed by this ADC policy and practice include the following:

     1.   “In late February 2010, [a named plaintiff] was attacked by other
          inmates and suffered eye injuries and fractures of his cheek bone,
          orbital bone around his eye, and upper jaw bone – fractures that,
          if not treated, result in the person’s face caving in, and in
          permanent disfigurement. Outside emergency room doctors
          advised that he be seen within a week by an ophthalmologist and
          plastic surgeon. Prison doctors submitted these referrals to the
          review committee, but they were not approved. Instead, [the
          named plaintiff] was sent to an oral surgeon, who operated on his
          face without an anesthesiologist present. [The named plaintiff]
          was over-sedated and had to have an antidote to be revived. His
          face was partially paralyzed due to nerve damage from the
          botched surgery and over-sedation, and his eyelid drooped,
          causing dryness to his cornea.”

     2.   “[A named plaintiff] waited more than two years to have a
          biopsy of [a] mass in his prostate, because contracts with outside
          providers were cancelled. By the time he was finally seen and
          treated, the cancer was much worse, resulting in more invasive
          surgery and the need to permanently use a catheter.”

     3.   “Beginning in 2010 [a named plaintiff] observed multiple masses
          growing on her breasts, mouth, and arms, and reported
          discomfort in her cervix. The masses were observable in
12                          PARSONS V. RYAN

    A third example of the Complaint’s medical care
allegations is the alleged statewide ADC policy and practice
of “not providing prisoners with timely emergency responses
and treatment, and [failing to provide] an adequate system for
responding to health care emergencies.” The Complaint
further alleges that “there is not an adequate number of on-
duty health care staff to respond to possible emergencies,”
“[d]efendants have not adequately trained security and health
care staff on how to handle health care emergencies,”
“[l]ower level medical staff, who serve as the first line of
response to prisoners’ requests for medical assistance, often
do not recognize when a prisoner is experiencing an
emergency,” and “even when properly responding to an
emergency, medical staff face barriers to providing timely
emergency assistance.”7


           physical examinations. She began experiencing frequent
           diarrhea, nausea, exhaustion, weight loss, pain, and other
           alarming systems. [She] has a family history of cancer and was
           treated for cancer in 2001. Starting in December 2010 she
           requested testing and a prison doctor ordered a referral to an
           oncologist. However, [she] was not sent to an oncologist and did
           not receive a CT scan until late September 2011. At that time the
           masses were described as ‘lighting [the CT scan] up like a
           Christmas tree,’ and the specialist orders biopsies and a
           colonoscopy . . . . She still has not seen an oncologist or had
           biopsies.”
 7
     Here, the plaintiffs’ examples include the following:

      1.   “In July 2010, correctional officers at the Tucson prison stood by
           and watched a severely mentally ill prisoner . . . bleed to death
           after his second suicide attempt . . . . When an internal
           investigator asked one officer, ‘So you guys just stood around for
           23 minutes and watched this guy bleed to death?’, the officer
           stated that his response was to call [the inmate’s] name and to try
           to elicit a reaction.”
                         PARSONS V. RYAN                                13

    Turning to the dental care claims, the Complaint alleges
that the defendants “have a policy and practice of failing to
provide medically necessary dental services.” It further
alleges that “prisoners wait months or years for basic dental
treatment and suffer significant pain and other harm,” “the
primary service provided by Defendants is tooth extraction,
even if a much less invasive procedure . . . is medically
appropriate and necessary,” and “prisoners who are fortunate
enough to get fillings are not given permanent fillings, but
rather temporary fillings that are not designed to last more
than a few months at most.” The Complaint contains
allegations concerning several inmates who have faced “the
horrible dilemma of saving a tooth and suffering pain, or
ending the pain and losing a tooth that otherwise could be
saved.”


   2.   “In October 2011, a prisoner at the Eyman prison collapsed in his
        living unit from a heart attack. Other prisoners yelled for
        security staff to contact medical staff. Officers told the prisoners
        to ‘wait and see what happens,’ and did not summon help or
        provide assistance to the stricken prisoner. In desperation,
        another inmate checked the prisoner’s pulse, and finding none,
        began to perform CPR. After a few minutes, the prisoner began
        breathing again. Only then did officers summon medical staff.
        Three hours later, the prisoner was sent from the medical unit
        back to his living unit and told he had a medical appointment in
        a few days. The prisoner had another heart attack the next day
        and died.”

   3.   “In May 2011, a prisoner who was four months pregnant began
        experiencing painful contractions and spotting blood, and went
        to Perryville’s medical unit. The staff person on duty told her it
        was nothing serious, that her problems were ‘all in your head,’
        and that she could not see a clinician for evaluation or treatment.
        She was sent back to her living unit, and she continued to
        experience great pain and cramping for an hour and a half, until
        she miscarried.”
14                         PARSONS V. RYAN

     With respect to the mental health care claims, the
Complaint alleges that the defendants systematically “fail[]
to provide prisoners with adequate mental health care.” It
first alleges that the defendants have a policy and practice of
“denying treatment to or providing inadequate treatment to
prisoners with serious mental health needs.” It elaborates that
the defendants lack sufficient staff to treat mentally ill
inmates; that the defendants fail to monitor and provide
follow-up treatment after prescribing psychotropic
medications; that prisoners who are on psychotropic
medications that increase heat sensitivity are exposed to
dangerous levels of heat; and that the defendants rely on
unqualified nurses and medical assistants for ongoing
monitoring of prisoners on psychotropic drugs.8

   The Complaint then separately alleges that the defendants
“deprive suicidal and self-harming prisoners of basic mental
health care.” In support of this allegation, it charges that the


 8
     Here, the plaintiffs’ examples include the following:

      •   “On two separate occasions when [a named plaintiff] was placed
          in suicide watch for engaging in self-harming behavior and
          suffering severe side effects from a variety of psychotropic
          medications, he did not see a psychiatrist for stretches of five and
          seven months.”

      •   “In June 2008, [a named plaintiff] was prescribed Celexa, but did
          not receive it for nearly a year. He was also prescribed lithium;
          however, despite the need for close monitoring for side effects
          from the lithium, he was not seen by a doctor for three months.
          His lithium was renewed without [the named plaintiff] having
          seen a doctor for six months. In November 2009, [he] submitted
          a [health needs request] reporting that he was vomiting when
          given lithium without food. He was given Tums and was not
          seen by a doctor.”
                           PARSONS V. RYAN                            15

defendants “have a policy and practice of housing prisoners
with serious mental health needs in unsafe conditions that
heighten their risk of suicide,” and reports that ADC prisoners
have a suicide rate double the national average in state
prisons. The Complaint adds that, as a matter of statewide
policy and practice, ADC suicide watch facilities “offer no
meaningful treatment”; “suicide watch cells are often filthy,
with walls and food slots smeared with other prisoners’ blood
and feces, reeking of human waste”; suicide watch cells are
maintained at “very cold temperatures” while prisoners “are
stripped of all clothing and given only a stiff suicide smock
and a thin blanket, making the extreme cold even harder to
tolerate”; the defendants unjustifiably use chemical agents on
suicidal inmates; and the defendants provide inadequate
nutrition to inmates on suicide watch, force them awake every
ten to 30 minutes around the clock, and leave bright lights on
24 hours a day.9

    Finally, the Complaint alleges that the defendants have a
policy and practice “of confining thousands of prisoners in
isolation . . . in conditions of enforced idleness, social
isolation, and sensory deprivation.” It further alleges as

 9
     Here, the plaintiffs’ examples include the following:

      •   “[A named plaintiff] did not see a psychitratist for 11 months
          despite being placed on suicide watch multiple times.”

      •   “[Two named plaintiffs] have asthma and rely upon inhalers, and
          they have had asthma attacks from the regular use of pepper
          spray in the women’s suicide watch unit. On multiple occasions
          after she was pepper sprayed in the eyes, nose, and mouth, [one
          named plaintiff] was dragged to a shower, stripped naked, and
          sprayed with extremely cold water to rinse away the pepper
          spray; she was then left naked to wait for a new vest and
          blanket.”
16                    PARSONS V. RYAN

follows: “prisoners in isolation leave their cells no more than
three times a week, for a brief shower and no more than two
hours of ‘exercise’ in the ‘rec pen’ – a barren, windowless
concrete cell with high walls [and] no exercise equipment”;
“some prisoners in isolation receive no outdoor exercise at all
for months or years on end; others receive insufficient
exercise to preserve their physical and mental health”; “most
or all of these prisoners are held in cells with a solid steel
door and no window to the outside”; “cells are often
illuminated 24 hours a day”; “chronic sleep deprivation is
common”; “property is extremely limited”; “prisoners in
isolation often go months or years without any meaningful
human interaction”; and the defendants “deny[] prisoners in
isolation adequate nutrition.” The Complaint adds that the
harm to inmates’ mental and physical health from these
conditions is “exacerbated by the policy and practice of
Defendants of failing to provide adequate mental health care
staffing and treatment.”

    In sum, the lengthy and comprehensive complaint in this
case alleges that there exist a number of statewide, uniform
ADC policies and practices concerning health care and
isolation units, and that these policies and practices expose all
members of the proposed class and subclass to a substantial
risk of serious harm.

     B. Discovery Material

    The plaintiffs also supported their motion for class
certification with documents obtained from the defendants
during discovery. For example, they submitted a letter from
ADC to Wexford dated September 21, 2012 in which ADC
identified serious and systemic deficiencies in Wexford’s
provision of health care to ADC inmates. In this letter, the
                     PARSONS V. RYAN                        17

ADC Contract Beds Operations Director stated that an ADC
review had revealed that “a significant number of inmates
may not have been receiving their medications as prescribed
[in July and August 2012] due to expired prescription(s) and
inappropriate renewals or refills,” describing these “8,358”
prescriptions as a “critical issue” and “grave concern to the
ADC.” After surveying other compliance concerns, the letter
proceeded to identify a number of “non-compliance issues”
regarding Wexford’s provision of health care in ADC
facilities, such as:

   •   “Inadequate staffing levels in multiple program areas
       at multiple locations,” resulting in “inappropriate
       scheduling gaps in on-site medical coverage,
       including In-Patient Component” and “[s]taffing
       levels forcing existing staff to work excessive hours,
       creating fatigue risks”;

   •   “Incorrect, incomplete, inconsistent medication
       administration or documentation of care provided,”
       including a “backlog of prescription medication
       expiration review,” “incorrect or incomplete
       pharmacy prescriptions,” “inappropriate
       discontinuation/change of medication,” “inconsistent
       or contradictory medication refill and/or return
       procedures,” and “inconsistent provision of release,
       transfer, and/or renewal medications”; and

   •   A “quantitative decrease in routine institutional care,”
       including a “backlog of provider line appointments,”
       “untimely handling of Health Needs Requests,” and
       “backlog/cancellation of outside specialty
       consultations”
18                    PARSONS V. RYAN

On October 1, 2012, Wexford replied with a letter in which
it condemned the low quality of ADC’s preexisting programs.
It described “long-standing issues, embedded into ADC
health care policy and philosophy,” and noted that ADC’s
health care system was “extremely poor,” “dysfunctional,”
“sub-standard,” and rife with “deficiencies.”

    This assessment of ADC policies and practices governing
the provision of health care to inmates is echoed by other
discovery materials. For example, a February 2011 e-mail
from the psychiatrist supervisor at one ADC complex warned
of “abysmal staffing” and cautioned that he was “circling the
drain.” In a similar vein, an August 2012 ADC memo
concluded that psychiatry staffing was “grossly insufficient”
and “so limited that patient safety and orderly operation of
[ADC] facilities may be significantly compromised.” Dozens
of other contract monitor reports from August 2012 offered
similar assessments, as did a Wexford staffing review
undertaken in November 2012, five months after Wexford
had taken over the provision of health care services in ADC
facilities. Wexford’s comprehensive review concluded that,
of 762 budgeted full time employee positions, only 567
positions had been filled. It also revealed that, for higher-
level providers, such as physicians, psychiatrists, dentists,
nurse practitioners, and management-level health care staff,
the overall vacancy rate across ADC facilities exceeded 50%.

     A survey of the quality of health care provision at ADC
facilities, also completed in November 2012, bristled with
criticism: “Insufficient coverage which only allows for
basically emergency care . . . now reaching a critical state for
both routine visits and chronic care follow-ups . . . no filled
dentist positions at this complex”; “There is no nurses line
being conducted in Central Unit”; “The [Health Needs
                      PARSONS V. RYAN                        19

Requests for mental health services] are not being triaged by
qualified mental health professionals during the required time
frame . . . [Inmates referred to a psychiatric provider] are not
being seen as required due to limited staffing”; “Staffing
continues to be of primary concern. In nursing alone, the
Lewis complex is 5.9 RN’s below staffing expectations and
8 LPN’s below staffing expectations”; “Nurseline is back-
logged out three weeks . . . Provider line is back-logged out
2 months . . . Charts requiring Provider review total roughly
70 charts”; and “At the current level there [are] not enough
providers to serve an inmate population of 4200+.” The rest
of the ADC and Wexford documents submitted by the
plaintiffs paint an equally grim picture of ADC’s operations
from 2009 through the time this case was filed.

   C. Expert Reports

    The plaintiffs submitted four expert reports, none of
which was rebutted by the defendants. Each of these experts
based his report on an examination of major portions of the
evidentiary record that the parties compiled in the district
court.

    Dr. Robert L. Cohen, an expert in prison health care,
court-appointed monitor in several other similar cases, and
member of the New York City Board of Corrections,
concluded that the defendants have placed prisoners “at
serious risk of harm, and in some cases, death” by “failing to
manage, support, supervise, and administer medical care to
prisoners in the ten state facilities.” The defendants, he
stated, “operate a top-down centralized health care system”
and “any local policies developed at the prison level must be
consistent with departmental policies.” Cohen noted that this
centralized system is nonetheless “highly dysfunctional,”
20                   PARSONS V. RYAN

adding that “there is a system-wide practice of not following
the [ADC’s formal] policies and procedures because, among
other things, [the] defendants have failed to provide adequate
staffing, supervision and resources to promote compliance.”
He elaborated that “written policies and procedures are often
viewed by providers and their supervisors as setting
unrealistic requirements, and therefore are ignored.”

     Cohen reported that, instead of following their formal
procedures, ADC’s prison facilities maintain “a policy and
practice of not providing adequate medical professional
staffing,” “a practice of not complying with [ADC’s]
requirement that health care records be reviewed within 12
hours of an inmate’s arrival,” “a practice and unwritten policy
of delaying and/or denying prisoners access to necessary care
for serious medical needs,” “a practice and unwritten policy
of not providing sufficient, trained staff to competently
respond to emergencies,” a “practice and unwritten policy of
failing to supervise, manage and support medication
distribution,” and a “practice of keeping chaotic, inaccurate,
and disorganized records throughout the state.” These
“extensive problems,” he opined, “are systemic, and are
similar to problems [he has] encountered in other prison class
action lawsuits where [he has] been an expert.” As a result of
these statewide policies and practices, Cohen concluded,
“medical care delivery in [ADC] poses a substantial risk of
serious harm to prisoners who require medical care.”

    Dr. Jay D. Shulman, a dentist with extensive experience
practicing in and examining military, educational, and
correctional dentistry programs, reviewed the ADC’s dental
system and offered a highly critical assessment: “[T]he
consistently inadequate care documented in the records I
reviewed is attributable to systemic problems caused by
                        PARSONS V. RYAN                             21

inadequate and poorly monitored policies and procedures in
the ADC’s Dental Department.”              Shulman carefully
summarized and then broadly criticized ADC’s policies and
practices “with regard to staffing, inmate health requests, pain
management, dental appliances, tooth extraction, and
informed consent,” explaining that they “combine into a
system that fails to adequately identify, or properly and
timely treat, dental issues experienced by inmates.” These
failures, he remarked, “place all inmates at risk not only of
preventable pain, but also of tooth decay and unnecessary loss
of teeth.” Shulman added that ADC policies “themselves
[fall] below the standard of care” and that “regular practices
often fall even further short.”

     In his report, Shulman singled out for particularly strong
criticism ADC’s “de facto [tooth] extraction only policy,” its
“policy or practice of failing to employ sufficient dental
staffing,”10 its failure to “ensure appropriate classification and
treatment of patients reporting dental issues,” its absence of
“timelines for routine treatment,”11 and its failure adequately
to treat “chewing difficulty” that can cause pain and
nutritional problems. These and the other issues he
identified, Schulman concluded, are “attributable to systemic
problems, primarily, inadequate staffing and inadequate and
poorly monitored policies and procedures.”



 10
   Shulman noted that the systemwide ADC ratio as of October 2012 was
1,384 inmates per dentist. He explained that the recommended ratio is
1,000:1, assuming that dental hygienist support is provided. ADC does
not employ any dental hygienists.
  11
     Shulman expressed grave concern that the treatment time to fill a
cavity in ADC facilities ranges from 85 to 292 days, with an average of
225 days.
22                        PARSONS V. RYAN

    Dr. Pablo Stewart, a professor of psychiatry with
extensive experience in correctional mental health care,
offered his “preliminary opinion” that “mental health care
services at ADC are in a state of disarray, and have been for
some time.” Observing that “all relevant policies and
procedures . . . are centralized with statewide application,”
Stewart opined that ADC’s “lack of a functioning mental
health program poses a substantial risk of serious harm to
prisoners with mental health needs.” He described a
“shortage of mental health staff, delays in providing or
outright failure to provide mental health treatment, and []
gross inadequacies in the provision of psychiatric
medications” as “statewide systemic problems,” noting that
“prisoners who need mental health care have already
experienced, or will experience, a serious risk of injury to
their health if these problems are not addressed.” Stewart
offered detailed analysis of these issues, as well as of
statewide problems involving policies and practices of
medication management, continuity of care, and protection of
prisoners on psychotropic medication from heat injury.12

    Stewart also addressed the issues of isolated confinement
and care for suicidal inmates. With respect to isolation, he
noted that ADC regularly houses mentally ill inmates in


     12
       Stewart noted that “there have been and continue to be severe
systemwide shortages of mental health staff in ADC,” that ADC “lacks a
reliable system for ensuring the delivery of prescribed medications,” that
“ADC does not have a reliable means for prisoners to make their mental
health needs known in a timely manner to qualified staff,” and that “ADC
lacks a reliable system to ensure that prisoners needing a higher level of
mental health care are transferred in a timely fashion to appropriate
facilities.” He supported each of these observations with references to the
voluminous evidentiary record—including, in many cases, references to
statements by ADC staff, officials, and contractors.
                     PARSONS V. RYAN                       23

isolation units—in accordance with ADC policy—even
though isolated confinement can be “devastating” to inmates
with “mental illness, such as psychotic disorders and major
mood disorders,” and can cause “severe deterioration in
mental health, self-harm, or suicide.” Turning to suicide
prevention, Stewart agreed with a senior ADC official who
admitted in his deposition that ADC maintains “a serious gap
in [its] ability to provide suicide prevention.” Stewart then
discussed what he characterized as serious flaws in ADC’s
policies and practices governing suicide watch, including the
absence of a requirement that inmates on suicide watch be
evaluated face-to-face by a psychiatrist and the policy of
allowing inmates to be removed from suicide watch by
unlicensed mental health staff members. He added that ADC
policies permitting the use of chemical agents on suicidal
inmates, and its practice of failing to ensure that its
correctional staff conducts regular security checks on
inmates, exacerbate the risk to which mentally ill inmates are
exposed in ADC facilities. Stewart ultimately concluded that
“the current state of mental health care services in [ADC]
poses a substantial risk of serious harm to prisoners who
require mental health care.” He explained that, although “not
all ADC prisoners will be harmed by these deficiencies in
exactly the same way—some will die, some will suffer injury
short of death, and some will be lucky enough to escape
permanent injury altogether,” the problems that he had
discovered in ADC’s “highly centralized” mental health care
system “are systemic in nature, and require systemic
solutions.”

    Dr. Craig Haney, a professor of social psychology with
extensive experience studying the psychological effects of
imprisonment and the consequences of solitary confinement,
assessed ADC’s isolation units. He first described, in detail,
24                       PARSONS V. RYAN

“a reasonably large and growing literature on the many ways
that solitary or so-called ‘supermax’ confinement can very
seriously damage the overall mental health of prisoners.” He
also emphasized that “mentally ill prisoners are particularly
at risk in these environments,” and that, as a result, “mental
health staff in most prison systems with which [he is] familiar
are charged with the responsibility not only of screening
prisoners in advance of their possibly being placed in
isolation (so that the mentally ill can be excluded) but also of
monitoring prisoners who are currently housed in solitary
confinement for signs of emerging mental illness (so that
they, too, can be removed).”

    Turning to ADC’s policies and practices, Haney opined
that “the failure of [ADC] to exclude categorically prisoners
who suffer from [severe mental illness] from its isolation
units is inconsistent with sound corrections and mental health
practice and places all such prisoners at substantial risk of
harm.” He added: “[T]he policies, practices and admissions
of ADC regarding conditions of confinement in its isolation
units . . . reflect the type of conditions that my own
experience and research—which is also supported by decades
of scientific research and study by others—have found to be
potentially detrimental to all human beings, regardless of pre-
existing mental illness. As such, all ADC prisoners are at risk
of substantial psychological harm under ADC’s current
isolation policy and practice.” Haney described the “stark
conditions of isolation” imposed by ADC as “harsh and
severe and precisely the kind that create a risk of substantial
harm for all the prisoners who are subjected to them.”13 He



    13
       Here, Haney emphasized ADC “policies that allow for 24 hour
illumination in some isolation cells; limited property, including lack of
                         PARSONS V. RYAN                              25

voiced particular alarm concerning ADC policies that allow
seriously mentally ill inmates to be housed in isolation,
ADC’s practice of inadequately monitoring those inmates due
to “policy shortfalls and chronic mental health understaffing,”
and ADC policies authorizing the use of chemical agents
against seriously mentally ill inmates (including those who
are on psychotropic medications). Haney concluded by
opining that “ADC’s apparent failure to put in place careful
mental health monitoring policies for all prisoners subject to
the extremely isolated conditions in their [isolation units]
places all prisoners subject to such conditions at an
unreasonable risk of harm.” “These harms,” he warned, “are
extremely serious and sometimes irreversible, including loss
of psychological stability, impaired mental functioning, self-
mutilation, and even death.”

    D. Declarations by the Named Plaintiffs

    In addition to the allegations in their complaint, the
documents obtained from ADC and Wexford in discovery,
and the expert reports, the plaintiffs also submitted
declarations describing their experiences with ADC’s policies
and practices governing health care and conditions of
confinement. These declarations by the named plaintiffs
were not submitted to support individual Eighth Amendment
claims; rather, the plaintiffs submitted these declarations as
evidence of the defendants’ unlawful policies and practices,
and as examples of the serious harm to which all inmates in
ADC custody are allegedly exposed. For example, Plaintiffs
Swartz, Licci, Jensen, Hefner, Wells, and Polson described
significant delays in receiving vital medical care, including


access to TVs or radios; infrequent, reduced calorie meals; and the years
and years that many prisoners spend in such conditions.”
26                    PARSONS V. RYAN

emergency and specialist care, as well as experiences in
which they were treated by nurses rather than doctors for
serious conditions, forced to wait months or years for
diagnostic tests, and denied timely access to medication.
Each of these plaintiffs reported suffering terrible pain—and
some also declared that these lengthy delays in and denials of
care led to permanent disfigurement or a need for more
radical, high-risk treatments. Each of the other named
plaintiffs submitted a sworn declaration attesting to his or her
experiences with ADC dental care, mental health care, or
isolation units.

                              III

    In a careful, thorough, and rigorous opinion, the district
court, considering all of this evidence, granted the plaintiffs’
motion for certification of a class and subclass. It then denied
a motion for reconsideration. It certified a class consisting of
“[a]ll prisoners who are now, or will in the future be,
subjected to the medical, mental health, and dental care
policies and practices of the ADC.” It also certified a
subclass consisting of “[a]ll prisoners who are now, or will in
the future be, subjected by the ADC to isolation, defined as
confinement in a cell for 22 hours or more each day or
confinement in [certain housing units].”

    In the district court, as in this court, the parties’ main
dispute concerned the requirement of commonality. The
district court determined that the plaintiffs could show
commonality, explaining that “the question common to all
members of the Class and the Subclass is whether
Defendants’ practices are deliberately indifferent to inmates’
health and safety in violation of the Eighth Amendment and
subjection to unconstitutional conditions of confinement in
                          PARSONS V. RYAN                              27

isolation units.” The district court emphasized that “the
problems identified in the provision of health care are not
merely isolated instances but, rather, examples of systemic
deficiencies that expose all inmates to a substantial risk of
serious harm.” In other words, it found that “the evidence
here suggests that the root cause of the injuries and threats of
injuries suffered by Plaintiffs is the systemic failures in the
provision of health care generally.” The district court deemed
this evidence to be “‘significant proof’ that ADC is operating
under a policy of providing deficient health care,” and
concluded that “the allegations of systemic deficiencies in
ADC’s provision of health care are sufficient to establish ‘a
system-wide practice or policy that affects all of the putative
class members.’” The district court then identified ten
specific ADC health care practices that allegedly expose all
members of the certified class to a substantial risk of harm to
which the defendants are deliberately indifferent, and seven
specific ADC isolation unit practices that allegedly do so the
same. These 17 statewide ADC practices, it concluded,
create the commonality required for the plaintiffs to proceed
by class and subclass form.

    After the district court denied a motion for
reconsideration, the defendants filed a Rule 23(f) petition
seeking interlocutory review of the district court’s class
certification order. See Chamberlan v. Ford Motor Co.,
402 F.3d 952, 959 (9th Cir. 2005) (per curiam) (describing
the legal standard applicable to discretionary authorization of
appeals under Rule 23(f)). This court granted that petition on
July 10, 2013 and the defendants perfected their appeal in a
timely manner.14

 14
    Both the district court and this court have denied motions filed by the
defendants to stay proceedings pending the outcome of this appeal.
28                   PARSONS V. RYAN

                STANDARD OF REVIEW

     We review a district court’s decision to certify a class
under Rule 23 for abuse of discretion and we review for clear
error any findings of fact upon which the district court relied
in its certification order. Hester v. Vision Airlines, Inc.,
687 F.3d 1162, 1171–72 (9th Cir. 2012). “When reviewing
a grant of class certification, we accord the district court
noticeably more deference than when we review a denial of
class certification.” Abdullah v. U.S. Sec. Associates, Inc.,
731 F.3d 952, 956 (9th Cir. 2013) (citing Wolin v. Jaguar
Land Rover N. Am., LLC, 617 F.3d 1168, 1171 (9th Cir.
2010)). “An abuse of discretion occurs when the district
court, in making a discretionary ruling, relies upon an
improper factor, omits consideration of a factor entitled to
substantial weight, or mulls the correct mix of factors but
makes a clear error of judgment in assaying them.” Stearns
v. Ticketmaster Corp., 655 F.3d 1013, 1018 (9th Cir. 2011)
(citing Wolin, 617 F.3d at 1171). Under the applicable
clearly erroneous standard of review, we reverse the district
court’s findings of fact only if they are “(1) illogical,
(2) implausible, or (3) without ‘support in inferences that may
be drawn from the record.’” Abdullah, 731 F.3d at 956
(quoting United States v. Hinkson, 585 F.3d 1247, 1262 (9th
Cir. 2009)). “Where there are two permissible views of the
evidence, the factfinder’s choice between them cannot be
clearly erroneous.” United States v. Working, 224 F.3d 1093,
1102 (9th Cir. 2000) (en banc) (citations and quotation marks
omitted).
                            PARSONS V. RYAN                            29

                              DISCUSSION

                                       I

    Class certification is governed by Federal Rule of Civil
Procedure 23. Under Rule 23(a), a party seeking certification
of a class or subclass must satisfy four requirements:
(1) numerosity; (2) commonality; (3) typicality; and
(4) adequacy of representation.15 “Class certification is
proper only if the trial court has concluded, after a ‘rigorous
analysis,’ that Rule 23(a) has been satisfied.” Wang v.
Chinese Daily News, Inc., 737 F.3d 538, 542–43 (9th Cir.
2013) (quoting Wal-Mart Stores, Inc, v. Dukes, 131 S. Ct.
2541, 2551 (2011)). The proposed class or subclass must also
satisfy the requirements of one of the sub-sections of Rule
23(b), “which defines three different types of classes.” Leyva

 15
      The full text of the subsection is as follows:

           (a) Prerequisites. One or more members of a class may
           sue or be sued as representative parties on behalf of all
           members only if:

                (1) the class is so numerous that joinder of all
                members is impracticable;

                (2) there are questions of law or fact common to
                the class;

                (3) the claims or defenses of the representative
                parties are typical of the claims or defenses of the
                class; and

                (4) the representative parties will fairly and
                adequately protect the interests of the class.

Fed. R. Civ. P. 23(a).
30                    PARSONS V. RYAN

v. Medline Industries, Inc., 716 F.3d 510, 512 (9th Cir. 2013).
In this case, the plaintiffs contend that their proposed class
and subclass meet the requirements of Rule 23(b)(2), which
requires that “the party opposing the class has acted or
refused to act on grounds that apply generally to the class, so
that final injunctive relief or corresponding declaratory relief
is appropriate respecting the class as a whole.”

    In evaluating whether a party has met the requirements of
Rule 23, we recognize that “Rule 23 does not set forth a mere
pleading standard.” Wal-Mart, 131 S. Ct. at 2551. We
therefore require a party seeking class certification to
“affirmatively demonstrate his compliance with the
Rule—that is, he must be prepared to prove that there are in
fact sufficiently numerous parties, common questions of law
or fact, etc.” Id. Similarly a party must affirmatively prove
that he complies with one of the three subsections of Rule
23(b).

     The defendants do not dispute that the plaintiffs meet the
requirements of numerosity and adequacy of representation
under Rule 23(a). They argue only that the district court
abused its discretion in concluding that the plaintiffs have
demonstrated commonality and typicality. The defendants
also contend that the plaintiffs have not met the requirements
of Rule 23(b)(2). They argue that the district court abused its
discretion in concluding that, assuming the plaintiffs prevail
on the merits, injunctive relief will be appropriate for the
whole class and subclass. We address each of these
arguments in turn and conclude that the district court did not
err in certifying the plaintiffs’ proposed class and subclass.
                      PARSONS V. RYAN                        31

                              II

    Rule 23(a)(2) requires “questions of law or fact common
to the class.” In Wal-Mart v. Dukes, the Supreme Court
announced that this provision requires plaintiffs to
“demonstrate that the class members ‘have suffered the same
injury,’” not merely violations of “the same provision of
law.” 131 S. Ct. at 2551 (quoting Gen. Tel. Co. of Sw. v.
Falcon, 457 U.S. 147,157 (1982)). Accordingly, plaintiffs’
claims “must depend upon a common contention” such that
“determination of [their] truth or falsity will resolve an issue
that is central to the validity of each one of the claims in one
stroke.” Id. at 2551. “What matters to class certification . . .
is not the raising of common ‘questions’—even in droves—
but, rather the capacity of a classwide proceeding to generate
common answers apt to drive the resolution of the litigation.”
Id. (quoting Richard A. Nagareda, Class Certification in the
Age of Aggregate Proof, 84 N.Y.U. L. Rev. 97, 132 (2009)).

    Plaintiffs need not show, however, that “every question in
the case, or even a preponderance of questions, is capable of
class wide resolution. So long as there is ‘even a single
common question,’ a would-be class can satisfy the
commonality requirement of Rule 23(a)(2).” Wang, 737 F.3d
at 544 (quoting Wal-Mart, 131 S. Ct. at 2556); see also
Mazza v. Am. Honda Motor Co., Inc., 666 F.3d 581, 589 (9th
Cir. 2012) (noting that “commonality only requires a single
significant question of law or fact”). Thus, “[w]here the
circumstances of each particular class member vary but retain
a common core of factual or legal issues with the rest of the
class, commonality exists.” Evon v. Law Offices of Sidney
32                        PARSONS V. RYAN

Mickell, 688 F.3d 1015, 1029 (9th Cir. 2012) (quotation
marks and citation omitted).16

    Here, the defendants argue that the district court erred in
concluding that the plaintiffs satisfied Rule 23(a)(2). Their
principal argument is that the district court abused its
discretion in concluding that the plaintiffs have identified
questions of law or fact common to the class. In their view,
“Eighth Amendment healthcare and conditions-of-
confinement claims are inherently case specific and turn on
many individual inquiries. That fact is an insurmountable
hurdle for a commonality finding because Wal-Mart instructs
that dissimilarities between class members ‘impede the
generation of common answers.’” Reply Br. at 4 (quoting
Wal-Mart, 131 S. Ct. at 2551, 2556). In other words—also
from the defendants—the plaintiffs fail Rule 23(a)(2)’s
commonality test because “a systemic constitutional violation
[of the sort alleged here] is a collection of individual
constitutional violations,” each of which hinges on “the




 16
     The defendants assert that the district court applied an incorrect, pre-
Wal-Mart legal standard to the class certification issue. That assertion is
incorrect. Although the district court did, at one point, cite a pre-Wal-
Mart case that no longer states the law, see Walsh v. Ford Motor Co., 130
F.R.D. 260, 268 (D.D.C. 1990), its analysis otherwise fully recognized
and addressed Wal-Mart and post-Wal-Mart cases. Its conclusion,
moreover, reflects a proper application of current law. Cf. D.G. ex rel.
Stricklin v. Devaughn, 594 F.3d 1188, 1200 (10th Cir. 2010) (“We refuse
to find an abuse of discretion where the district court is accused of not
talismanically reciting [Rule 23’s] exact language in applying the law to
the facts when it clearly understood the law it was required to apply and
accurately applied it.”).
                          PARSONS V. RYAN                               33

particular facts and circumstances of each case.”17 Id. at
9–10. This position amounts to a sweeping assertion that,
after Wal-Mart, Eighth Amendment claims can never be
brought in the form of a class action.18 The defendants’ view
rests, however, on a fundamental misunderstanding of Wal-
Mart, Eighth Amendment doctrine, and the plaintiffs’
constitutional claims.

    In this case, as in all class actions, commonality cannot be
determined without a precise understanding of the nature of
the underlying claims. See Amgen Inc. v. Connecticut Ret.
Plans & Trust Funds, 133 S. Ct. 1184, 1194–95 (2013)
(“Merits questions may be considered to the extent—but only
to the extent—that they are relevant to determining whether
the Rule 23 prerequisites for class certification are satisfied.”
(citation omitted)); Ellis v. Costco Wholesale Corp., 657 F.3d
970, 981 (9th Cir. 2011) (“[T]he merits of the class members’
substantive claims are often highly relevant when
determining whether to certify a class.”).19 As we recently


  17
      The cases cited in the defendants’ briefs, many of which involve
individuals challenging particular instances of medical treatment or
conditions of confinement, confirm that they (erroneously) view the
plaintiffs’ claims as ultimately little more than a conglomeration of many
such individual claims, rather than as a claim that central policies expose
all inmates to a risk of harm.
      18
      As the defendants put it, “[t]he very individualized nature of
inadequate health care and conditions-of-confinement claims makes it
very difficult, if not impossible, to satisfy Wal-Mart’s ‘one stroke’
standard.” Opening Br. at 25.
 19
    Of course, this does not mean that the plaintiffs must show at the class
certification stage that they will prevail on the merits. See, e.g., Amgen,
133 S. Ct. at 1194–95 (“Although we have cautioned that a court’s class-
certification analysis must be ‘rigorous’ and may ‘entail some overlap
34                        PARSONS V. RYAN

observed, “[t]o assess whether the putative class members
share a common question, the answer to which ‘will resolve
an issue that is central to the validity of each one of the [class
members’s] claims,’ we must identify the elements of the
class members’s case-in-chief.” Stockwell, 2014 WL
1623736, at *6 (quoting Wal-Mart, 131 S. Ct. at 2551). Here,
the defendants describe the plaintiffs’ claims as little more
than an aggregation of many claims of individual
mistreatment. See, e.g., Jett v. Penner, 439 F.3d 1091, 1096
(9th Cir. 2006). That description, however, rests upon a
misunderstanding of the plaintiffs’ allegations.              The
Complaint does not allege that the care provided on any
particular occasion to any particular inmate (or group of
inmates) was insufficient, see, e.g., Estelle v. Gamble,
429 U.S. 97, 104–05 (1976), but rather that ADC policies and
practices of statewide and systemic application expose all
inmates in ADC custody to a substantial risk of serious harm.

   This kind of claim is firmly established in our
constitutional law. As the Supreme Court recognized in
1993, “[t]hat the Eighth Amendment protects against future
harm to inmates is not a novel proposition.” Helling v.



with the merits of the plaintiff’s underlying claim,’ Rule 23 grants courts
no license to engage in free-ranging merits inquiries at the certification
stage.” (quoting Wal-Mart, 131 S. Ct. at 2551); Stockwell v. City & Cnty.
of San Francisco, No. 12-15070, 2014 WL 1623736, at *4 (9th Cir. Apr.
24, 2014) (“[D]emonstrating commonality does not require proof that the
putative class will prevail on whatever common questions it identifies.”);
Messner v. Northshore Univ. HealthSystem, 669 F.3d 802, 811 (7th Cir.
2012) (“[T]he court should not turn the class certification proceedings into
a dress rehearsal for the trial on the merits.”); Ellis, 657 F.3d at 983 n.8
(emphasizing that “whether class members could actually prevail on the
merits of their claims” is not a proper inquiry in determining “whether
common questions exist.”).
                      PARSONS V. RYAN                         35

McKinney, 509 U.S. 25, 33 (1993). Noting that it “would be
odd to deny an injunction to inmates who plainly proved an
unsafe, life-threatening condition in their prison on the
ground that nothing yet had happened to them,” Helling
squarely rejected the proposition, hinted at by the defendants
here, that “only deliberate indifference to current serious
health problems of inmates is actionable under the Eighth
Amendment.” Id. at 33, 34; see also id. at 33 (“We have
great difficulty agreeing that prison authorities may not be
deliberately indifferent to an inmate’s current health problems
but may ignore a condition of confinement that is sure or very
likely to cause serious illness and needless suffering the next
week or month or year.”). The Court then emphasized that
“[w]e would think that a prison inmate also could
successfully complain about demonstrably unsafe drinking
water without waiting for an attack of dysentery,” and that
prison officials may not be “deliberately indifferent to the
exposure of inmates to a serious, communicable disease on
the ground that the complaining inmate shows no serious
current symptoms.” Id. In Farmer v. Brennan, the Court
elaborated on Helling’s recognition that a “remedy for unsafe
conditions need not await a tragic event,” id., by holding that
“[a] prison official’s ‘deliberate indifference’ to a substantial
risk of serious harm to an inmate violates the Eighth
Amendment,” 511 U.S. 825, 828 (1994).

    Since Helling and Farmer, we have repeatedly recognized
that prison officials are constitutionally prohibited from being
deliberately indifferent to policies and practices that expose
inmates to a substantial risk of serious harm. See, e.g.,
Graves v. Arpaio, 623 F.3d 1043, 1049 (9th Cir. 2010)
(substantial risk of harm from exposure of pre-trial detainees
on psychotropic medication to extreme heat); Wallis v.
Baldwin, 70 F.3d 1074, 1076 (9th Cir. 1995) (substantial risk
36                   PARSONS V. RYAN

of harm from sustained exposure to asbestos). In fact, we
have recently reminded a district court of the difference
between a claim that an inmate has already suffered harm and
a claim that he has been exposed to a substantial risk of
serious harm. See Thomas v. Ponder, 611 F.3d 1144, 1151
n.5 (9th Cir. 2010) (“In its order, the district court
erroneously considers whether the prison officials were aware
that Thomas was ‘suffering serious harm from the
deprivation’ of exercise. The correct issue for consideration
is, however, whether the prison officials were subjectively
aware of a ‘serious risk of substantial harm.’” (citing Farmer,
511 U.S. at 837; Helling, 509 U.S. at 32)).

    In Brown v. Plata, the Supreme Court distinguished the
kind of systemic, future-oriented Eighth Amendment claim at
issue here from claims in which a past instance of
mistreatment is alleged to have violated the Constitution:

       Because plaintiffs do not base their case on
       deficiencies in care provided on any one
       occasion, this Court has no occasion to
       consider whether these instances of delay—or
       any other particular deficiency in medical care
       complained of by the plaintiffs—would
       violate the Constitution under Estelle v.
       Gamble, 429 U.S. 97, 104–105 (1976), if
       considered in isolation. Plaintiffs rely on
       systemwide deficiencies in the provision of
       medical and mental health care that, taken as
       a whole, subject sick and mentally ill
       prisoners in California to “substantial risk of
       serious harm” and cause the delivery of care
       in the prisons to fall below the evolving
       standards of decency that mark the progress of
                     PARSONS V. RYAN                        37

       a maturing society. Farmer v. Brennan,
       511 U.S. 825, 834 (1994).

Brown v. Plata, 131 S. Ct. 1910, 1925 n.3 (2011). Since
Plata, we have relied on this fundamental distinction to hold
that “where a California prisoner brings an independent claim
for injunctive relief solely on his own behalf for specific
medical treatment denied to him, Plata does not bar the
prisoner’s claim for injunctive relief.” Pride v. Correa,
719 F.3d 1130, 1137 (9th Cir. 2013). As we explained,
“[i]ndividual claims for injunctive relief related to medical
treatment are discrete from the claims for systemic reform
addressed in Plata.” Id.

    As the district court correctly recognized, the Eighth
Amendment claims in this case are of the same basic kind as
the claims in Helling, Farmer, Plata, and several of our own
precedents, including Graves and Wallis. In those cases,
courts have asked only whether the plaintiffs were exposed to
a substantial risk of harm to which prison officials were
deliberately indifferent—and have recognized that many
inmates can simultaneously be endangered by a single policy.
See Helling, 509 U.S. at 33 (unsafe drinking water); Graves,
623 F.3d at 1049 (heat exposure); Wallis, 70 F.3d at 1076
(asbestos); Hoptowit v. Spellman, 753 F.2d 779, 783–84 (9th
Cir. 1985) (substandard fire prevention).

    Here, a proper understanding of the nature of the
plaintiffs’ claims clarifies the issue of commonality. What all
members of the putative class and subclass have in common
is their alleged exposure, as a result of specified statewide
ADC policies and practices that govern the overall conditions
of health care services and confinement, to a substantial risk
of serious future harm to which the defendants are allegedly
38                   PARSONS V. RYAN

deliberately indifferent. As the district court recognized,
although a presently existing risk may ultimately result in
different future harm for different inmates—ranging from no
harm at all to death—every inmate suffers exactly the same
constitutional injury when he is exposed to a single statewide
ADC policy or practice that creates a substantial risk of
serious harm. See, e.g., Farmer, 511 U.S. at 834; Helling,
509 U.S. at 33; cf. Plata, 131 S. Ct. at 1923 (“For years the
medical and mental health care provided by California’s
prisons has fallen short of minimum constitutional
requirements and has failed to meet prisoners’ basic health
needs. Needless suffering and death have been the well-
documented result.”).

    The putative class and subclass members thus all set forth
numerous common contentions whose truth or falsity can be
determined in one stroke: whether the specified statewide
policies and practices to which they are all subjected by ADC
expose them to a substantial risk of harm. See Dukes, 131 S.
Ct. at 2551. The district court identified 10 statewide ADC
policies and practices to which all members of the class are
subjected, and seven statewide ADC policies and practices
which affect all members of the subclass. These policies and
practices are the “glue” that holds together the putative class
and the putative subclass; either each of the policies and
practices is unlawful as to every inmate or it is not. That
inquiry does not require us to determine the effect of those
policies and practices upon any individual class member (or
class members) or to undertake any other kind of
individualized determination.

    The district court thus did not abuse its discretion in
deciding to structure the litigation in the form of a class of
“all prisoners who are now, or will in the future be, subjected
                         PARSONS V. RYAN                              39

to the medical, mental health, and dental care policies and
practices of the ADC.” After all, every inmate in ADC
custody is necessarily subject to the same medical, mental
health, and dental care policies and practices of ADC. And
any one of them could easily fall ill, be injured, need to fill a
prescription, require emergency or specialist care, crack a
tooth, or require mental health treatment. It would indeed be
surprising if any given inmate did not experience such a
health care need while serving his sentence. Thus, every
single ADC inmate faces a substantial risk of serious harm if
ADC policies and practices provide constitutionally deficient
care for treatment of medical, dental, and mental health
needs.20 As Justice Kennedy explained in Plata, inadequate
health care in a prison system endangers every inmate: “Even
prisoners with no present physical or mental illness may
become afflicted, and all prisoners in California are at risk so
long as the State continues to provide inadequate care . . . .
[P]risoners who are not sick or mentally ill . . . [are] in no
sense [] remote bystanders in California’s medical care
system. They are that system’s next potential victims.”
131 S. Ct. at 1940.

    Critically, the district court also identified 10 policies and
practices to which all members of the certified class are
exposed. In so doing, it confirmed that the class members are
as one in their exposure to a particular and sufficiently well-
defined set of allegedly illegal policies and practices, rather
than only in their advancement of a general Eighth




  20
      The same analysis applies to the part of the district court’s order
certifying the isolation subclass, which it defined with respect to seven
policies and practices.
40                         PARSONS V. RYAN

Amendment legal theory.21 Each of these 10 policies and
practices affords a distinct basis for concluding that members
of the putative class satisfy commonality, as all members of
the class are subject identically to those same policies and
practices, and the constitutionality of any given policy and
practice with respect to creating a systemic, substantial risk
of harm to which the defendants are deliberately indifferent
can be answered in a single stroke.22

    For example, with respect to the putative class, the
plaintiffs allege that they are placed at risk of serious harm by
a policy and practice of severe under-staffing across all ADC
medical care facilities. As a result of this statewide policy
and practice, they allege, the quality and availability of care
across all ADC facilities is constitutionally deficient. This
allegation presents questions of law and fact common to all
members of the putative class. While no inmate can know in


  21
     Of course, district courts must be wary of framing common questions
so generally that they encompass myriad, distinct claims. Here, the
district court complied with that requirement: there is a single claim—
exposure to substantial risk of serious harm due to systemic policies and
practices—that can be proven (or not) in a single stroke with respect to
any or all of the certified policies. The district court might also, in the
alternative, have certified numerous separate classes or subclasses,
separating out groups of policies and practices, but we cannot say that it
abused its discretion in deciding that a single class and a single subclass
would be the most efficacious and appropriate structure for this litigation.
  22
      The defendants devote little effort to challenging the policies and
practices one at a time. They devote nearly all of their argument to a
broad attack on the certification of any class in this case, saying relatively
little about the propriety of certifying a class as to any particular policy
and practice. In any event, we have reviewed each of the 17 policies and
practices and conclude that certification is appropriate as to each of them
with respect to commonality.
                         PARSONS V. RYAN                              41

advance whether he will receive adequate and timely care in
the event that he falls ill or is injured, or know exactly what
form of harm he will suffer from the absence of such care,
every single inmate has allegedly been placed at substantial
risk of future harm due to the general unavailability of
constitutionally adequate care. The question whether ADC’s
staffing policies pose a risk of serious harm to all ADC
prisoners can thus be answered as to the entire class “in one
stroke.” Wal-Mart, 131 S. Ct. at 2551. Either ADC employs
enough nurses and doctors to provide adequate care to all of
its inmates or it does not do so; there is no need for an
inmate-by-inmate inquiry to determine whether all inmates in
ADC custody are exposed to a substantial risk of serious
harm by ADC staffing policies. See M.D. v. Perry, 294
F.R.D. 7, 45 (S.D. Tex. 2013) (holding, in a prisoner class
action suit, that “[t]he fact of whether [prison] policies
subject class members to an unreasonable risk of harm, and
whether that risk is so unreasonable as to rise to a
constitutional violation, can be proven on the basis of
classwide evidence without individualized inquiries.”). As
exemplified by Plata, claims of this kind, involving detailed
factual and legal allegations of specified systemic
deficiencies in prison conditions giving rise to a substantial
risk of serious harm, have long been brought in the form of
class actions lawsuits.23 See also, e.g., Armstrong v. Davis,


  23
     The defendants’ insistence that commonality is defeated by individual
variations in preexisting conditions, demand for medical care, and
response to treatment is incorrect. Even if some inmates are exposed to
a greater or idiosyncratic risk of harm by the policy and practice of not
hiring enough staff to provide adequate medical care to all inmates, that
single policy and practice allegedly exposes every single inmate to a
serious risk of the same basic kind of harm. Thus, while Wal-Mart
instructs that “[d]issimilarities within the proposed class . . . have the
potential to impede the generation of common answers,” 131 S. Ct. at
42                        PARSONS V. RYAN

275 F.3d 849 (9th Cir. 2001). In fact, without such a means
of challenging unconstitutional prison conditions, it is
unlikely that a state’s maintenance of prison conditions that
violate the Eighth Amendment could ever be corrected by
legal action.

    The same is true of the plaintiffs’ allegations concerning
conditions of confinement in the isolation units. For
example, the plaintiffs allege that it is the policy and practice
of ADC to provide inmates in isolation with constitutionally
deficient food and nutrition. See Foster v. Runnels, 554 F.3d
807, 814 (9th Cir. 2009) (“The sustained deprivation of food
can be cruel and unusual punishment when it results in pain
without any penological purpose.” (citation omitted)). They
support that claim with references to formal ADC policies,
admissions by ADC officials in discovery documents,
declarations by the named plaintiffs, allegations in the
Complaint, and Dr. Haney’s expert report. This claim will
not stand or fall based on variations in how hungry each
member of the putative subclass is, or on each individual’s
particular dietary needs (e.g., some may be kosher, others
may be vegetarians). While those variations undoubtedly
exist and affect how particular inmates experience and
respond to ADC policies and practice, they do not defeat
commonality because the plaintiffs’ claim is that ADC, as a
matter of formal policy and systemic practice, regularly
provides a level of nutrition that is so inadequate that it


2551, the acknowledged dissimilarities here between members of the
proposed class do not in any way bear on or disrupt what they allegedly
have in common, and it is that common exposure to ADC policies that
constitutes the core factual predicate of their shared legal claim. In other
words, ADC staffing policies for all of its facilities are either
constitutional or unconstitutional as to all inmates—that legal contention
can be answered in one stroke.
                          PARSONS V. RYAN                              43

exposes any inmate who is presently in ADC isolation or will
in the future be placed in isolation to a substantial risk of
serious harm. Some inmates may not actually be harmed, but
they are all allegedly exposed to a risk of harm that is, in its
own right, a constitutional injury amenable to resolution in a
class action.24

    Wal-Mart, decided shortly after Plata, clarified that class
certification is appropriate only where the plaintiffs’ claims
rest on a “common contention” whose “truth or falsity will
resolve an issue that is central to the validity of each one of
the claims in one stroke.” Wal-Mart, 131 S. Ct. at 2551.
Although the defendants assert that Wal-Mart prohibits class
certification here, a comparison of Wal-Mart and this case
strongly supports affirmance. Wal-Mart concluded that a
proposed Title VII class of 1.5 million female employees,
challenging discretionary decisions made by managers in
3,400 stores across the country, failed Rule 23(a)(2). Id. at
2551–57. It reasoned that the plaintiffs, who alleged a
general corporate policy of allowing discretion by local
managers, lacked “a common answer to the crucial question

  24
     To take another example from the isolation subclass, the plaintiffs
allege that they are exposed to a substantial risk of harm by inadequate
psychiatric monitoring due to chronic understaffing. They support this
claim with detailed allegations in the Complaint; declarations from several
named plaintiffs; internal ADC documents in which ADC staff
psychiatrists warn of dangerous understaffing and ADC accuses Wexford
of failing properly to provide mental health care staff; Wexford reports
that reveal gross understaffing of psychiatric positions; and the expert
reports of Dr. Haney and Dr. Stewart. For this claim, too, the question is
whether all inmates in isolation units—all of whom are at high risk of
mental health issues by the very fact of their confinement in isolation—are
placed at risk of harm by the absence of enough mental health care
providers to treat them. This question can be answered as to every
member of the subclass in one stroke.
44                    PARSONS V. RYAN

why was I disfavored.” Id. at 2552. It ultimately concluded
that the plaintiffs’ effort to “sue about literally millions of
employment decisions at once” thwarted commonality
because “demonstrating the invalidity of one manager’s use
of discretion will do nothing to demonstrate the invalidity of
another’s.” Id. at 2252, 2254. This case is different than
Wal-Mart in every respect that matters. It involves uniform
statewide practices created and overseen by two individuals
who are charged by law with ultimate responsibility for
health care and other conditions of confinement in all ADC
facilities, not a grant of discretion to thousands of managers.
It involves 33,000 inmates in the custody of a single state
agency, not millions of employees scattered throughout the
United States. It looks to whether current conditions in ADC
facilities create a risk of future harm, not to the varied reasons
for millions of decisions made in the past. Whereas there
may have been many answers in Wal-Mart to the question
“why was I disfavored?,” here there is only a single answer
to questions such as “do ADC staffing policies and practices
place inmates at a risk of serious harm?”

    It is therefore not surprising that, in deciding analogous
class certification motions since Wal-Mart, numerous courts
have concluded that the commonality requirement can be
satisfied by proof of the existence of systemic policies and
practices that allegedly expose inmates to a substantial risk of
harm. See, e.g., Chief Goes Out v. Missoula Cnty., No. 12
Civ. 155, 2013 WL 139938, at *5 (D. Mont. Jan. 10, 2013)
(“[C]ourts have long recognized that, in prison condition
cases like this one, the injury is the [deprivation] itself, not
just the negative effects resulting from the [deprivation] . . . .
[O]ther courts have certified classes of inmates claiming
unconstitutional deprivation of outdoor exercise, and scores
of courts have certified classes of prisoners claiming other
                      PARSONS V. RYAN                          45

unconstitutional prison conditions.”); Butler v. Suffolk Cnty.,
289 F.R.D. 80, 98 (E.D.N.Y. 2013) (“Whether the County
was aware of and deliberately indifferent to the conditions at
the [prison] is a common question subject to class-wide
resolution.”); Hughes v. Judd, No. 12 Civ. 568, 2013 WL
1821077, at *23 (M.D. Fla. Mar. 27, 2013) report and
recommendation adopted as modified, No. 12 Civ. 568, 2013
WL 1810806 (M.D. Fla. Apr. 30, 2013) (“Plaintiffs’ claims
related to these [prison] conditions are capable of class-wide
resolution: Plaintiffs seek permanent injunctive and
declaratory relief that would enjoin allegedly unconstitutional
behavior as applied to the entire class. Importantly, the
questions of law are applicable in the same manner to each
potential class member . . . . Each class member, if
proceeding separately against Defendants, would need to
meet the same test under the Eighth and Fourteenth
Amendments to prevail.”); Rosas v. Baca, No. 12 Civ. 428,
2012 WL 2061694, at *3 (C.D. Cal. June 7, 2012) (Pregerson,
J.) (“In a civil rights suit such as this one . . . commonality is
satisfied where the lawsuit challenges a system-wide practice
or policy that affects all of the putative class members.
Under such circumstances, individual factual differences
among class members pose no obstacle to commonality.”);
Indiana Prot. & Advocacy Servs. Comm’n v. Comm’r,
Indiana Dep’t of Correction, No. 08 Civ. 1317, 2012 WL
6738517, at *18 (S.D. Ind. Dec. 31, 2012) (“The mentally ill
prisoners here, have demonstrated through a wealth of
evidence, that the class is united by the common question of
whether the lack of treatment and isolated living conditions
in IDOC facilities violate the Eighth Amendment.”); see also
Armstrong, 275 F.3d at 868.

   In the related context of suits challenging a state’s
provision of social services to children in its protection,
46                    PARSONS V. RYAN

courts have employed similar logic while concluding that
Rule 23(a)(2) is satisfied. As the Tenth Circuit explained
while affirming certification of a class challenging
Oklahoma’s foster care system:

       Named Plaintiffs presented more than
       conclusory statements that OKDHS’s agency-
       wide monitoring policies and practices, or
       lack thereof, create a risk of harm shared by
       the entire class. All class members, by virtue
       of being in OKDHS’s foster care, are subject
       to the purportedly faulty monitoring policies
       of OKDHS, regardless of their individual
       differences; therefore, all members of the
       class are allegedly exposed to the same
       unreasonable risk of harm as a result of
       Defendants’ unlawful practices. Though each
       class member may not have actually suffered
       abuse, neglect, or the risk of such harm,
       Defendants’ conduct allegedly poses a risk of
       impermissible harm to all children in OKDHS
       custody.

DG ex rel. Stricklin v. Devaughn, 594 F.3d 1188, 1196 (10th
Cir. 2010); see also, e.g., M.D., 294 F.R.D. at 44 (“To what
extent caseworkers are overworked, whether this overwork is
significant enough to subject the members of the General
Class to an unconstitutionally unreasonable risk of harm, and
whether the State has sufficient mechanisms in place to
mitigate those risks are the issues central to the Plaintiffs’
claim. Resolving them will determine the validity of the
common General Class Fourteenth Amendment claim in ‘one
stroke.’ If, for example, it is proven at trial that caseworkers
are not so overworked that they fail to provide
                          PARSONS V. RYAN                               47

constitutionally adequate care, then that will resolve all of the
class members’ claims at once; the State’s policies regarding
caseworker workloads would be found not to violate the
Fourteenth Amendment.”); D.G. ex rel. Strickland v.
Yarbrough, 278 F.R.D. 635, 644 (N.D. Okla. 2011)
(“[P]laintiffs have presented ‘significant proof’ that DHS has
a policy or practice of failing to adequately monitor the safety
of plaintiff children causing significant harm and risk of harm
to their safety.”); Connor B., ex rel. Vigurs v. Patrick, 278
F.R.D. 30, 34 (D. Mass. 2011) (“Plaintiffs have alleged
specific and overarching systemic deficiencies . . . that place
children at risk of harm. These deficiencies, rather than the
discretion exercised by individual case workers, are the
alleged causes of class members’ injuries, because they
undermine [the Department of Children and Family’s] ability
to timely and effectively implement case workers’ decisions.
These systemic shortcomings provide the ‘glue’ that unites
Plaintiffs’ claims.”).25


  25
     One court has used similar logic to conclude that a putative class of
mentally ill individuals who are unnecessarily institutionalized in state
hospitals or who are at serious risk of unnecessary institutionalization in
those facilities satisfied Rule 23(a)(2)’s commonality requirement. See
Kenneth R. ex rel. Tri-Cnty. CAP, Inc./GS v. Hassan, 293 F.R.D. 254, 267
(D.N.H. 2013), appeal dismissed (Mar. 14, 2014) (“The plaintiffs have
also shown that common questions susceptible to common answers are
present. For instance, whether there is a systemic deficiency in the
availability of community-based services, and whether that deficiency
follows from the State’s policies and practices, are questions central to
plaintiffs’ theory of the case. These questions will, necessarily, be
answered similarly for every class member. And, whether the systemic
conditions, if shown to exist, expose all class members to a serious risk of
unnecessary institutionalization, including continued unnecessary
institutionalization, is a central and common contention whose resolution
will defeat or advance the claims of all class members, whether
institutionalized or not. In short, these common questions can be answered
48                        PARSONS V. RYAN

    To be sure, this line of precedent does not hold that utterly
threadbare allegations that a group is exposed to illegal
policies and practices are enough to confer commonality. As
Wal-Mart made clear, Rule 23(a) is not a pleading standard;
rather, it requires proof that there are “in fact . . . common
questions of law or fact.” 131 S. Ct. at 2551; see also
Comcast Corp. v. Behrend, 133 S. Ct. 1426, 1432 (2013)
(noting that “it may be necessary for the court to probe
behind the pleadings before coming to rest on the certification
question” (quotation marks and citations omitted)); DL v.
District of Columbia, 713 F.3d 120, 126 (D.C. Cir. 2013)
(concluding that commonality had not been shown where the
plaintiffs in a putative IDEA class action had not identified a
“single or uniform policy or practice that bridges all their
claims”); M.D. v. Perry, 675 F.3d 832, 844 (5th Cir. 2012)
(cautioning that “mere allegations of systemic violations of
the law . . . will not automatically satisfy Rule 23(a)’s
commonality requirement” (quotation marks and citations
omitted)).

   Here, however, the plaintiffs have met, and indeed far
exceeded, that requirement.26 The materials that they
submitted to the district court—which included four thorough
and unrebutted expert reports, the detailed allegations in the
74-page complaint, hundreds of internal ADC documents,
and declarations by the named plaintiffs—constituted more



either ‘yes’ or ‘no’ for the entire class, and the answers will not vary by
individual class members.” (quotation marks and citations omitted)).
  26
     We emphasize that our conclusions concerning the adequacy of the
plaintiffs’ evidence and arguments at this early stage in the litigation do
not constitute judgments concerning the ultimate merits of the plaintiffs’
allegations. See Amgen, 133 S. Ct. at 1194–95; Messner, 669 F.3d at 811.
                           PARSONS V. RYAN                                 49

than sufficient evidence at this stage in the litigation of the
existence of the statewide ADC policies and practices that
allegedly expose all members of the putative class to a
substantial risk of serious harm.27 Those policies and
practices, moreover, are defined with sufficient precision and
specificity; they involve particular and readily identifiable
conduct on the part of the defendants, such as failing to hire
enough medical staff, failing to fill prescriptions, denying
inmates access to medical specialists, adopting a de facto
“extraction only” policy for dental issues, and depriving
suicidal and mentally ill inmates access to basic mental health
care.28 Compare M.D., 675 F.3d at 844 (noting that
commonality is not shown when plaintiffs allege an
amorphous claim of undefined and unspecified systemic
misconduct). Accordingly, the district court did not abuse its


 27
   As the district court observed, many of these documents, including the
expert reports and the internal ADC and Wexford memos and staffing
reviews, demonstrate that the challenged ADC policies and practices are
uniform across facilities and statewide in their scope.
  28
     The defendants argue that a few of the “practices” identified by the
district court are not defined with sufficient precision. The district court
carefully considered this argument and firmly rejected it, reasoning that,
unlike in cases where “there was simply insufficient evidence propelling
the plaintiffs’ isolated allegations of mistreatment into a plausible claim
of systemic deficiencies,” “the evidence here suggests that the root cause
of the injuries and threats of injuries suffered by Plaintiffs is the systemic
failures in the provision of health care generally.” The district court added
that “Plaintiffs’ expert declarations, largely unrebutted at this juncture, are
sufficient to establish that ADC’s practices or customs in the provision of
health care rise to the level of deliberate indifference that places inmates
at a substantial risk of serious harm.” We conclude that the district court
did not clearly err in making these factual findings concerning practices
across all ADC facilities, nor did it abuse its discretion in concluding that
those factual findings are sufficient under Rule 23(a)(2) to establish the
existence of the complained of ADC-wide policies and practices.
50                        PARSONS V. RYAN

considerable discretion in finding that, for purposes of Rule
23(a)(2), the evidence submitted by the plaintiffs adequately
demonstrated the existence of the challenged statewide
policies and practices.29

     In sum, we conclude that the district court did not abuse
its discretion in determining that the plaintiffs’ claims depend
upon common questions of law or fact that are answerable in
one stroke. A clear line of precedent, stretching back long
before Wal-Mart and unquestionably continuing past it,
firmly establishes that when inmates provide sufficient
evidence of systemic and centralized policies or practices in
a prison system that allegedly expose all inmates in that
system to a substantial risk of serious future harm, Rule
23(a)(2) is satisfied. Here, the plaintiffs’ Eighth Amendment
claims satisfy all of those criteria. The factual and legal

 29
    The parties dispute whether the “significant proof” standard, described
in Wal-Mart as the standard applicable to one means of bridging a “gap”
in evidence of systemic discrimination, applies to the plaintiffs’ arguments
here that the alleged uniform ADC policies and practices exist. Courts
have taken different views of whether Wal-Mart’s significant proof
standard applies to all class certification decisions or only to claims
alleging systemic discrimination. Compare Jamie S. v. Milwaukee Pub.
Sch., 668 F.3d 481, 498 (7th Cir. 2012) (applying “significant proof”
requirement to an alleged policy of violating the requirements of the
IDEA) with Jermyn v. Best Buy Stores, L.P., 276 F.R.D. 167, 172
(S.D.N.Y. 2011) (holding that “these additional requirements are designed
for and unique to the context of employment discrimination”). We need
not resolve that dispute, however, because under either a “significant
proof” standard or any lesser evidentiary standard, we would conclude that
“the breadth and consistency of class counsel’s initial evidence places the
district court’s finding of commonality well within that court’s discretion.”
Staton v. Boeing Co., 327 F.3d 938, 954 (9th Cir. 2003). That conclusion
is required both by the strength of the plaintiffs’ evidence and by the
defendants’ near-utter failure to respond to it with evidence of their own,
such as expert reports or internal studies.
                      PARSONS V. RYAN                        51

questions that they present can be answered “yes” or “no” in
one stroke as to the entire class, dissimilarities among class
members do not impede the generation of common answers
to those questions, and the capacity of classwide proceedings
to drive the resolution of this litigation cannot be doubted.
See Wal-Mart, 131 S. Ct. at 2551–52. The claims, defenses,
relevant facts, and substantive law are all common across the
class. Accordingly, certification of the class and subclass was
appropriate with respect to Rule 23(a)(2)’s requirement of
commonality.

                              III

    Rule 23(a)(3) requires that “the claims or defenses of the
representative parties are typical of the claims or defenses of
the class.”     “Under the rule’s permissive standards,
representative claims are ‘typical’ if they are reasonably co-
extensive with those of absent class members; they need not
be substantially identical.” Hanlon v. Chrysler Corp.,
150 F.3d 1011, 1020 (9th Cir. 1998). The test of typicality is
“whether other members have the same or similar injury,
whether the action is based on conduct which is not unique to
the named plaintiffs, and whether other class members have
been injured by the same course of conduct.” Hanon v.
Dataproducts Corp., 976 F.2d 497, 508 (9th Cir. 1992).
Thus, “[t]ypicality refers to the nature of the claim or defense
of the class representative, and not to the specific facts from
which it arose or the relief sought.” Id.

    As the Supreme Court recognized in Wal-Mart, Rule
23(a)’s commonality and typicality requirements occasionally
merge: “Both serve as guideposts for determining whether
under the particular circumstances maintenance of a class
action is economical and whether the named plaintiff’s claim
52                    PARSONS V. RYAN

and the class claims are so interrelated that the interests of the
class members will be fairly and adequately protected in their
absence.” 131 S. Ct. at 2551 n.5. We expressed a similar
point over a decade earlier in Armstrong v. Davis, a case in
which we also clarified how to analyze typicality in cases like
this one:

        Where the challenged conduct is a policy or
        practice that affects all class members, the
        underlying issue presented with respect to
        typicality is similar to that presented with
        respect to commonality, although the
        emphasis may be different. In such a case,
        because the cause of the injury is the
        same—here, the [Board of Prison Term’s]
        discriminatory policy and practice—the
        typicality inquiry involves comparing the
        injury asserted in the claims raised by the
        named plaintiffs with those of the rest of the
        class. We do not insist that the named
        plaintiffs’ injuries be identical with those of
        the other class members, only that the
        unnamed class members have injuries similar
        to those of the named plaintiffs and that the
        injuries result from the same, injurious course
        of conduct.

275 F.3d at 868–69.

     Here, the named plaintiffs are all inmates in ADC
custody. Each declares that he or she is being exposed, like
all other members of the putative class, to a substantial risk of
                           PARSONS V. RYAN                                53

serious harm by the challenged ADC policies and practices.30
See Hanon, 976 F.2d at 508. The named plaintiffs thus allege
“the same or [a] similar injury” as the rest of the putative
class; they allege that this injury is a result of a course of
conduct that is not unique to any of them; and they allege that
the injury follows from the course of conduct at the center of
the class claims.31 See id. Further, given that every inmate in
ADC custody is highly likely to require medical, mental
health, and dental care, each of the named plaintiffs is
similarly positioned to all other ADC inmates with respect to
a substantial risk of serious harm resulting from exposure to
the defendants’ policies and practices governing health care.
Cf. Hanlon, 150 F.3d at 1020 (holding that “the broad
composition of the representative parties” can “vitiate[] any
challenge founded on atypicality”). It does not matter that the
named plaintiffs may have in the past suffered varying
injuries or that they may currently have different health care
needs; Rule 23(a)(3) requires only that their claims be
“typical” of the class, not that they be identically positioned
to each tother or to every class member. See Ellis, 657 F.3d
at 985 n.9 (“Differing factual scenarios resulting in a claim of
the same nature as other class members does not defeat

 30
    With respect to the subclass, several of the named plaintiffs have been
held in the isolation units whose conditions, as a matter of policy and
practice, allegedly violate the Eighth Amendment. The analysis of
typicality for the class in this paragraph is equally applicable to typicality
for the subclass.
  31
     The defendants’ argument that each named plaintiffs’ description of
past injuries must be treated as its own claim for Eighth Amendment
relief, potentially subject to unique defenses, rests on the same
misunderstanding of the nature of the plaintiffs’ claims that infected their
objections to commonality. The named plaintiffs allege that they are all
exposed to a substantial risk of serious harm, not that their particular
experiences in the past violated the Eighth Amendment.
54                    PARSONS V. RYAN

typicality.”). Accordingly, we conclude that the district court
did not abuse its discretion in determining that the plaintiffs
have satisfied the typicality requirement of Rule 23(a).

                              IV

    Rule 23(b)(2) requires that “the party opposing the class
has acted or refused to act on grounds that apply generally to
the class, so that final injunctive relief or corresponding
declaratory relief is appropriate respecting the class as a
whole.” Although we have certified many different kinds of
Rule 23(b)(2) classes, the primary role of this provision has
always been the certification of civil rights class actions. See
Amchem Products, Inc. v. Windsor, 521 U.S. 591, 614 (1997)
(“Rule 23(b)(2) permits class actions for declaratory or
injunctive relief where ‘the party opposing the class has acted
or refused to act on grounds generally applicable to the class.’
Civil rights cases against parties charged with unlawful,
class-based discrimination are prime examples.” (citations
omitted)); Walters v. Reno, 145 F.3d 1032, 1047 (9th Cir.
1998) (“Rule 23(b)(2) was adopted in order to permit the
prosecution of civil rights actions.”); Baby Neal for & by
Kanter v. Casey, 43 F.3d 48, 63 (3d Cir. 1994) (“The writers
of Rule 23 intended that subsection (b)(2) foster institutional
reform by facilitating suits that challenge widespread rights
violations of people who are individually unable to vindicate
their own rights.” (citations omitted)). As Wright and Miller
have explained:

       [S]ubdivision (b)(2) was added to Rule 23 in
       1966 in part to make it clear that civil-rights
       suits for injunctive or declaratory relief can be
       brought as class actions . . . [T]he class suit is
       a uniquely appropriate procedure in civil-
                     PARSONS V. RYAN                       55

       rights cases, which generally involve an
       allegation of discrimination against a group as
       well as the violation of rights of particular
       individuals. By their very nature, civil-rights
       class actions almost invariably involve a
       plaintiff class, although they may also be
       brought against a defendant class . . .

Wright & Miller, 7AA Fed. Prac. & Proc. Civ. § 1776 (3d
ed.). Of course, we do not interpret Rule 23(b)(2) in a
manner that would prevent certification of the kinds of civil
rights class action suits that it was intended to authorize.

   Thus, following Rule 23(b)(2)’s text and purpose, courts
have repeatedly invoked it to certify classes of inmates
seeking declaratory and injunctive relief for alleged
widespread Eighth Amendment violations in prison systems:

       [I]t should be noted that a common use of
       Rule 23(b)(2) is in prisoner actions brought to
       challenge various practices or rules in the
       prisons on the ground that they violate the
       constitution. For example, Rule 23(b)(2) class
       actions have been utilized to challenge prison
       policies or procedures alleged to . . . violate
       the prisoners’ Eighth Amendment rights to be
       free from cruel and unusual punishment.

Id. at § 1776.1; see also, e.g., Butler, 289 F.R.D. at 101
(certifying Rule 23(b)(2) class of prisoners alleging systemic
Eighth Amendment violations); Hughes, 2013 WL 1821077,
at *20 (same); Rosas, 2012 WL 2061694, at *5 (same);
Indiana Prot. & Advocacy Servs. Comm’n, 2012 WL
6738517 at *18 (same).
56                       PARSONS V. RYAN

    Here, the plaintiffs seek declaratory and injunctive
remedies. In their prayer for relief, the plaintiffs request that
the defendants be ordered “to develop and implement, as soon
as practical, a plan to eliminate the substantial risk of serious
harm that prisoner Plaintiffs and members of the Plaintiff
Class suffer due to Defendants’ inadequate medical, mental
health, and dental care, and due to Defendants’ isolation
policies.” The plaintiffs then specify 10 separate issues that
the defendants should be required to address in any court-
enforced plan designed to satisfy their alleged remedial
obligations. These issues include staffing, screening, chronic
care, emergency response, and medication and supplies.32
The plaintiffs’ expert reports also include descriptions of the
kinds of court-ordered changes in ADC policy and practice
that could alleviate the alleged systemic Eighth Amendment
violations, as well as affirmations by all four experts that, in
their experience, court-ordered injunctive relief could
effectively alleviate the deficiencies in ADC policies and
practices identified in their reports.

   The district court concluded that the plaintiffs’ claims
“for injunctive relief stemming from allegedly
unconstitutional conditions of confinement are the
quintessential type of claims that Rule 23(b)(2) was meant to
address.” It explained that “the claims of systemic
deficiencies in ADC’s health care system and
unconstitutional conditions of confinement in isolation units
apply to all proposed class members,” and firmly rejected the


     32
       Under “Staffing,” for example, the plaintiffs request that the
defendants be required to ensure that “Staffing shall be sufficient to
provide prisoner Plaintiffs and the Plaintiff Class with timely access to
qualified and competent clinicians who can provide routine, urgent,
emergent, and specialty health care.”
                      PARSONS V. RYAN                         57

defendants’ contention that “any proposed injunction here
would be crafted at a stratospheric level of abstraction.” It
added that “the remedy in this case would not lie in providing
specific care to specific inmates,” but rather “the level of care
and resources would be raised for all inmates.” “Thus,” it
concluded, “if successful, a proposed injunction addressing
those [policies and] practices would . . . prescribe a standard
of conduct applicable to all class members.” In other words,
“relief for some inmates would necessarily result in
injunctive relief for all inmates.”

    The district court did not abuse its broad discretion in
determining that the plaintiffs have satisfied Rule 23(b)(2).
In Wal-Mart, the Supreme Court summarized Rule 23(b)(2)’s
requirements as follows:

        The key to the (b)(2) class is “the indivisible
        nature of the injunctive or declaratory remedy
        warranted—the notion that the conduct is such
        that it can be enjoined or declared unlawful
        only as to all of the class members or as to
        none of them.” In other words, Rule 23(b)(2)
        applies only when a single injunction or
        declaratory judgment would provide relief to
        each member of the class. It does not
        authorize class certification when each
        individual class member would be entitled to
        a different injunction or declaratory judgment
        against the defendant . . . .

131 S. Ct. at 2557 (citation omitted). These requirements are
unquestionably satisfied when members of a putative class
seek uniform injunctive or declaratory relief from policies or
practices that are generally applicable to the class as a whole.
58                        PARSONS V. RYAN

See Rodriguez v. Hayes, 591 F.3d 1105, 1125 (9th Cir. 2010).
That inquiry does not require an examination of the viability
or bases of the class members’ claims for relief, does not
require that the issues common to the class satisfy a Rule
23(b)(3)-like predominance test, and does not require a
finding that all members of the class have suffered identical
injuries.33 See id.; Walters v. Reno, 145 F.3d 1032, 1047 (9th

 33
      As Wright & Miller observe:

          The term ‘generally applicable’ has been said to signify
          that the party opposing the class does not have to act
          directly against each member of the class. The key is
          whether the party’s actions would affect all persons
          similarly situated so that those acts apply generally to
          the whole class . . . .

          [C]ourts have interpreted this requirement to mean that
          the party opposing the class either has acted in a
          consistent manner toward members of the class so that
          the opposing party’s actions may be viewed as part of
          a pattern of activity, or has established or acted
          pursuant to a regulatory scheme common to all class
          members. This is consistent with the intention of the
          Advisory Committee, which stated in its Note to the
          1966 amendment of Rule 23 that: “Action or inaction is
          directed to a class within the meaning of this
          subdivision even if it has taken effect or is threatened
          only as to one or a few members of the class, provided
          it is based on grounds which have general application
          to the class.” All the class members need not be
          aggrieved by or desire to challenge defendant’s conduct
          in order for some of them to seek relief under Rule
          23(b)(2). What is necessary is that the challenged
          conduct or lack of conduct be premised on a ground
          that is applicable to the entire class.

Fed. Prac. & Proc. Civ. at § 1775 (quotation marks and footnotes
omitted).
                           PARSONS V. RYAN                                59

Cir. 1998). Rather, as the text of the rule makes clear, this
inquiry asks only whether “the party opposing the class has
acted or refused to act on grounds that apply generally to the
class.” Rule 23(b)(2).

    In this case, all members of the putative class and
subclass are allegedly exposed to a substantial risk of serious
harm by a specified set of centralized ADC policies and
practices of uniform and statewide application. While each
of the certified ADC policies and practices may not affect
every member of the proposed class and subclass in exactly
the same way, they constitute shared grounds for all inmates
in the proposed class and subclass. See Rodriguez, 591 F.3d
at 1125–26; Walters, 145 F.3d at 1047.34 In sum, by allegedly



 34
    See also, e.g., M.D. ex rel. Stukenberg v. Perry, 675 F.3d 832, 847–48
(5th Cir. 2012) (“[T]he [Rule (b)(2)] class claims could conceivably be
based on an allegation that the State engages in a pattern or practice of
agency action or inaction—including a failure to correct a structural
deficiency within the [child protective services] agency, such as
insufficient staffing—“with respect to the class,” so long as declaratory or
injunctive relief settling the legality of the [State’s] behavior with respect
to the class as a whole is appropriate.” (citations omitted)); D.G., 594 F.3d
at 1201 (“Here the ‘grounds’ that have general application to the class are
that all class members have been placed in [the Oklahoma Department of
Human Services’s] foster care program and, as such, caseworkers monitor
all class members in a system that allegedly fails to ensure they do not
carry caseloads so demanding that they cannot monitor class members
adequately.”); Baby Neal, 43 F.3d at 64 (“Plaintiffs have alleged that
systemic failure causes the DHS to violate various mandates under federal
statutory and constitutional provisions. Because the children in the system
are comparably subject to the injuries caused by this systemic failure, even
if the extent of their individual injuries may be affected by their own
individual circumstances, the challenge to the system constitutes a legal
claim applicable to the class as a whole. An order forcing the
[Department of Human Services] to comply with their statutory and
60                        PARSONS V. RYAN

establishing systemic policies and practices that place every
inmate in ADC custody in peril, and by allegedly doing so
with deliberate indifference to the resulting risk of serious
harm to them, the defendants have acted on grounds that
apply generally to the proposed class and subclass, rendering
certification under Rule 23(b)(2) appropriate.

    The relief requested by the plaintiffs also conforms with
Rule 23(b)(2)’s requirement that “final injunctive relief or
corresponding declaratory relief is appropriate respecting the
class as a whole.” See Wal-Mart, 131 S. Ct. at 2557 (stating
that Rule 23(b)(2) “does not authorize class certification
when each individual class member would be entitled to a
different injunction or declaratory judgment against the
defendant”). Contrary to the defendants’ assertion that each
inmate’s alleged injury is amenable only to individualized
remedy, every inmate in the proposed class is allegedly
suffering the same (or at least a similar) injury and that injury
can be alleviated for every class member by uniform changes
in statewide ADC policy and practice. See, e.g., D.G.,
594 F.3d at 1201 (“Named Plaintiffs allege the same injury
on behalf of all class members as a result of excessive
caseloads—exposure to an impermissible risk of harm . . . .
To remedy this alleged harm, Named Plaintiffs propose an
injunction requiring OKDHS assign no more than 15 foster
children to each caseworker . . . . As the district court noted,
such an injunction applies to the proposed class as a whole
without requiring differentiation between class members.”);
Marisol A. v. Giuliani, 126 F.3d 372, 378 (2d Cir. 1997)
(“Defendants argue that because the plaintiffs have alleged
differing harms requiring individual remedies, no injunction


constitutional mandates would constitute relief generally applicable to the
entire putative class.”).
                          PARSONS V. RYAN                                61

will be appropriate for the entire class . . . . We disagree.
Insofar as the deficiencies of the child welfare system stem
from central and systemic failures, the district court did not
abuse its discretion in certifying a 23(b)(2) class at this stage
of the litigation.” (citations omitted)). For example, every
inmate in ADC custody is allegedly placed at risk of harm by
ADC’s policy and practice of failing to employ enough
doctors—an injury that can be remedied on a class-wide basis
by an injunction that requires ADC to hire more doctors, with
the exact number of necessary additional hires to be
determined by the district court if, after a trial, it ultimately
concludes that the defendants engaged in unlawful conduct.
Thus, considering the nature and contours of the relief sought
by the plaintiffs, the district court did not abuse its discretion
in concluding that a single injunction and declaratory
judgment could provide relief to each member of the
proposed class and subclass.35



  35
           Remarkably, the defendants do not cite a single Ninth Circuit
case in support of their argument that the district court erred in certifying
the class and subclass under Rule 23(b)(2). Instead, they rely on a Tenth
Circuit case suggesting that, at the class certification stage, plaintiffs
seeking certification under Rule 23(b)(2) might be required to offer a
fairly detailed description of the injunctive relief that they seek. See
Shook v. Board of County Commissioners of County of El Paso, 543 F.3d
597 (10th Cir. 2008) (“Shook II”). In that case, while noting that “we very
well may have made a different decision had the issue been presented to
us as an initial matter,” and that the plaintiffs had “eschewed any effort to
give content” to the terms of their proposed injunction, the court held that
a district court had not abused its discretion in declining to certify a Rule
23(b)(2) class where the proposed injunction had been formulated at “a
stratospheric level of abstraction” and required inmate-by-inmate
assessments. Id. at 603, 604, 606. The court also noted a few reasons
why district courts, exercising their discretion, might require more detailed
descriptions of systemic reform injunctions. See id. at 604–07.
62                         PARSONS V. RYAN

                           CONCLUSION

   The district court acted well within its broad discretion in
concluding that the putative class and subclass satisfy the


     The defendants’ reliance on that case here is ill-founded. First, we
seriously doubt that the degree of specificity suggested in Shook II’s wide-
ranging dicta is properly required at the class certification stage for a Rule
23(b)(2) class. That is particularly true in prison cases, given that an
injunction in any such case must closely track the violations established
by the evidence at trial, that any such relief must comply with the PLRA’s
extensive requirements, that prison officials must play a role in shaping
injunctions, that ultimate proof of some violations but not others might
easily change the structure of a remedial plan, that conditions in prisons
might change over the course of litigation, and that the class certification
hearing is not a dress rehearsal of the trial on the merits (let alone a dress
rehearsal of the remedy proceedings). The better approach in a prison
conditions case is for the district court, exercising its discretion and
following Rule 23, to ask whether the plaintiffs’ proposed relief “is
appropriate respecting the class as a whole.” That requirement ordinarily
will be satisfied when plaintiffs have described the general contours of an
injunction that would provide relief to the whole class, that is more
specific than a bare injunction to follow the law, and that can be given
greater substance and specificity at an appropriate stage in the litigation
through fact-finding, negotiations, and expert testimony. Second, since
Shook II, several courts, including the Tenth Circuit, have observed that
certification of a Rule 23(b)(2) class is warranted under circumstances
highly analogous to those present here. See, e.g., M.D., 675 F.3d at 847
(Fifth Circuit); D.G., 594 F.3d at 1188 (Tenth Circuit). Finally, even if we
were to apply Shook II and all of its dicta, we would still affirm. After all,
we are reviewing for abuse of discretion a grant of class certification—
unlike the Shook II court, which took pains to emphasize that it might well
have certified the class before it on de novo review and that the level of
detail that it described merely explained why the lower court opinion was
not “beyond the pale.” 543 F.3d at 604. Further, here the plaintiffs have
described their injunction in more specific terms than did the plaintiffs in
Shook II, and they have fleshed out that description by introducing four
expert reports that explain which policies are deficient and what sorts of
policy remedies could alleviate the alleged violations.
                   PARSONS V. RYAN                    63

requirements of Rule 23. We therefore affirm the district
court’s certification order.

   AFFIRMED.
