                           PUBLISHED

UNITED STATES COURT OF APPEALS
               FOR THE FOURTH CIRCUIT


KIMBERLY MILLER,                         
                   Plaintiff-Appellee,
                v.
AT&T CORPORATION, a foreign
corporation,

                                         
             Defendant-Appellant.
                                             No. 00-1277
EQUAL EMPLOYMENT ADVISORY
COUNCIL; CHAMBER OF COMMERCE, of
the United States of America;
SECRETARY OF LABOR;
COMMUNICATIONS WORKERS OF
AMERICA, AFL-CIO,
                      Amici Curiae.
                                         
KIMBERLY MILLER,                         
                   Plaintiff-Appellee,
                v.
AT&T CORPORATION, a foreign
corporation,

                                         
             Defendant-Appellant.
                                             No. 00-1928
EQUAL EMPLOYMENT ADVISORY
COUNCIL; CHAMBER OF COMMERCE, of
the United States of America;
SECRETARY OF LABOR;
COMMUNICATIONS WORKERS OF
AMERICA, AFL-CIO,
                      Amici Curiae.
                                         
2                  MILLER v. AT&T CORPORATION
           Appeals from the United States District Court
     for the Southern District of West Virginia, at Charleston.
              Joseph Robert Goodwin, District Judge.
                          (CA-98-808-2)

                     Argued: January 24, 2001

                       Decided: May 7, 2001

       Before WILKINS and MICHAEL, Circuit Judges, and
      Claude M. HILTON, Chief United States District Judge
     for the Eastern District of Virginia, sitting by designation.



Affirmed by published opinion. Judge Wilkins wrote the majority
opinion, in which Judge Michael joined. Chief Judge Hilton wrote a
dissenting opinion.


                             COUNSEL

ARGUED: Catherine Michele Kirk, AT&T CORPORATION, Mor-
ristown, New Jersey, for Appellant. Barbara Eby Racine, UNITED
STATES DEPARTMENT OF LABOR, Washington, D.C., for
Amicus Curiae Secretary. Lonnie Carl Simmons, LAW OFFICE OF
P. RODNEY JACKSON, Charleston, West Virginia, for Appellee.
ON BRIEF: Laura A. Kaster, AT&T CORPORATION, Basking
Ridge, New Jersey; William E. Robinson, Michael A. Kawash, ROB-
INSON & MCELWEE, Charleston, West Virginia, for Appellant.
Henry L. Solano, Solicitor of Labor, Steven J. Mandel, Associate
Solicitor, William J. Stone, Senior Trial Attorney, UNITED STATES
DEPARTMENT OF LABOR, Washington, D.C., for Amicus Curiae
Secretary. Ann Elizabeth Reesman, Corrie L. Fischel, MCGUINESS,
NORRIS & WILLIAMS, L.L.P., Washington, D.C., for Amicus
Curiae Advisory Council; Stephen A. Bokat, Robin S. Conrad, Sussan
Mahallati Kysela, NATIONAL CHAMBER LITIGATION CENTER,
INC., Washington, D.C., for Amicus Curiae Chamber of Commerce.
Mary K. O’Melveny, Washington, D.C.; Ray A. Byrd, SHRADER,
                    MILLER v. AT&T CORPORATION                         3
BYRD & COMPANION, P.L.L.C., Wheeling, West Virginia, for
Amicus Curiae Communications Workers.


                              OPINION

WILKINS, Circuit Judge:

   AT&T Corporation (AT&T) appeals orders of the district court
finding it liable for violating Kimberly Miller’s rights under the Fam-
ily and Medical Leave Act (FMLA) of 1993, 29 U.S.C.A. §§ 2601-
2654 (West 1999), and awarding back pay and attorneys’ fees. With
respect to liability, AT&T contends that it did not violate the FMLA
because the illness for which Miller sought FMLA leave—an episode
of the flu—was not a serious health condition as defined by the Act
and implementing regulations; that if Miller’s flu was a serious health
condition under the applicable regulations, those regulations are con-
trary to congressional intent and are therefore invalid; and that in any
event, Miller failed to comply with AT&T’s procedures for the grant-
ing of FMLA leave. With respect to the award of back pay, AT&T
claims that the award should have been limited by after-acquired evi-
dence and Miller’s failure to mitigate her damages.1 We conclude that
none of AT&T’s challenges warrants reversal, and we therefore
affirm.

                                   I.

               A. The Family and Medical Leave Act

   The FMLA entitles an eligible employee to as many as 12 weeks
of unpaid leave per year for "a serious health condition that makes the
employee unable to perform the functions of the position of such
employee."2 29 U.S.C.A. § 2612(a)(1)(D). The Act defines "serious
health condition" as
  1
     AT&T also requests, in the event we rule in its favor on any of the
grounds raised, that we vacate the award of attorneys’ fees and remand
for reconsideration. Because we reject all of AT&T’s challenges to the
determination of liability and the award of back pay, there is no reason
to disturb the award of attorneys’ fees.
   2
     An "eligible employee" is one who, with certain exceptions not rele-
vant here, has been employed for at least 12 months and who has at least
4                   MILLER v. AT&T CORPORATION
    an illness, injury, impairment, or physical or mental condi-
    tion that involves—

            (A) inpatient care in a hospital, hospice, or
         residential medical care facility; or

           (B) continuing treatment by a health care pro-
         vider.

Id. § 2611(11). Thus, as is relevant here, an eligible employee is enti-
tled to FMLA leave for an illness that incapacitates the employee
from working and for which the employee receives "continuing treat-
ment," a term the FMLA does not define.

   The FMLA grants the Secretary of Labor authority to promulgate
regulations implementing the Act. See id. § 2654. Pursuant to this
authority, the Secretary promulgated the following regulation:

    A serious health condition involving continuing treatment
    by a health care provider includes . . . :

      (i) A period of incapacity (i.e., inability to work . . .) of
    more than three consecutive calendar days . . . that also
    involves:

           (A) Treatment two or more times by a health
         care provider . . . ; or

            (B) Treatment by a health care provider on at
         least one occasion which results in a regimen of
         continuing treatment under the supervision of the
         health care provider.

29 C.F.R. § 825.114(a)(2) (2000). The regulations further provide that
"treatment" "includes (but is not limited to) examinations to deter-

1,250 hours of service during the previous 12 months. See 29 U.S.C.A.
§ 2611(2)(A). AT&T has never disputed that Miller was an "eligible
employee" under the FMLA.
                    MILLER v. AT&T CORPORATION                         5
mine if a serious health condition exists and evaluations of the condi-
tion." 29 C.F.R. § 825.114(b) (2000).

   The FMLA allows an employer to require that a request for leave
for an employee’s serious health condition be supported by a certifi-
cation from the employee’s health care provider. See 29 U.S.C.A.
§ 2613(a). Among other things, the employer may require that the
certification include "appropriate medical facts" regarding the condi-
tion. Id. § 2613(b)(3). If the employer doubts the validity of a certifi-
cation, it may require the employee to obtain a second opinion at the
employer’s expense. See id. § 2613(c)(1). In the event of a conflict
between the two opinions, the employer may require the employee to
obtain a third opinion, again at the employer’s expense. See id.
§ 2613(d)(1). The opinion of the third health care provider is binding
on both parties. See id. § 2613(d)(2).

  The FMLA provides a private cause of action to an employee
whose request for FMLA leave has been improperly denied by an
employer. See id. § 2617(a). A prevailing employee may be awarded
damages, liquidated damages, and equitable relief such as reinstate-
ment. See id. § 2617(a)(1). The court must also award attorneys’ fees
and costs to a prevailing plaintiff. See id. § 2617(a)(3).

            B. AT&T’s Attendance and Leave Policies3

                                   1.

   AT&T considers satisfactory attendance to be a condition of
employment, and it expects all employees to be at work on time on
scheduled work days and to remain at their posts during scheduled
hours. However, AT&T does not have specific standards for deter-
mining whether an employee’s attendance is unsatisfactory. Rather, a
determination of unsatisfactory attendance is made based upon the
reasons for the employee’s absences, the circumstances involved, the
employee’s record with AT&T, and the employee’s length of service.
Absences are either "chargeable" or "non-chargeable," and only
  3
   The facts regarding AT&T’s attendance and leave policies, and the
facts regarding Miller’s employment history, see infra Part I.C., are
undisputed.
6                   MILLER v. AT&T CORPORATION
chargeable absences are considered in determining whether an
employee’s attendance is satisfactory. Absences covered by the
FMLA are considered non-chargeable.

   Employee attendance is monitored by an attendance administrator,
who reviews the employee’s record after each absence. If this review
demonstrates that the employee’s attendance is unsatisfactory, the
attendance administrator may recommend disciplinary action to the
employee’s supervisor. In evaluating an employee’s attendance, a
supervisor may not consider an absence as to which there is a pending
request for FMLA leave.

   AT&T employs a progressive disciplinary system for attendance
matters. The first step in this system is a "development session," dur-
ing which the employee is reminded of the requirements of AT&T’s
attendance policy. If the employee’s attendance does not improve, the
employee is engaged in a "serious discussion" about his attendance.
A serious discussion includes a warning that the employee’s atten-
dance problems must be corrected if formal disciplinary action is to
be avoided. If the serious discussion proves ineffective, the employee
is issued a "letter of warning" and subsequently, if necessary, a "final
letter of warning." An employee may be terminated for a chargeable
absence incurred while under a final letter of warning.

                                   2.

   AT&T has implemented procedures for employees who seek
FMLA leave. In order to request FMLA leave, an employee must sub-
mit two forms. The first, a Family and Medical Leave of Absence
Notification Form ("FMLA-1"), requires the employee to provide
general information regarding the reason for the requested leave and
the expected duration of the leave if known. The form is completed
by a supervisor, who verifies that the employee is eligible for FMLA
leave, i.e., that the employee has worked the requisite number of
hours during the preceding 12-month period and has not exhausted all
FMLA leave. The second form, a Certification of Health Care Pro-
vider ("FMLA-2"), requires the employee’s doctor to provide infor-
mation regarding the employee’s health condition. Item 3 on the
                     MILLER v. AT&T CORPORATION                          7
FMLA-2 requires the physician to indicate which of six categories of
serious health conditions the employee’s illness falls into.4

   Once completed, both forms are submitted to AT&T’s Health
Affairs office in Morristown, New Jersey. The forms are first
reviewed for completeness, then forwarded to a case manager. The
case manager, a registered nurse, recommends granting or denying
the request for leave based upon the submitted information. If the sub-
mission is not complete, or if clarification is required, further infor-
mation may be requested from the employee or the employee’s
doctor. A final decision regarding the request for leave is made by an
operations manager, who then communicates the decision to the
employee and the employee’s supervisor. If a request for FMLA leave
is denied, the employee may resubmit the request. However, resub-
mitted requests are rarely granted.

                       C. Miller’s Employment

                                    1.

   Miller was employed by AT&T as an account representative from
September 1990 until her termination in March 1997. In November
1994, Miller’s supervisor, Steve Snedegar, engaged Miller in a seri-
ous discussion about her attendance record.5 Snedegar warned Miller
that continued absences could result in the issuance of a letter of
warning, and he encouraged her to make use of FMLA leave. Snede-
  4
     AT&T’s FMLA-2 is quite similar to Form WH-380, promulgated by
the Secretary of Labor as an example of an appropriate format for
requesting medical certification of FMLA leave. See 29 C.F.R. Pt. 825,
App. B (2000); see also 29 C.F.R. § 825.306(a) (2000) (noting that the
Department of Labor "has developed an optional form (Form WH-380,
as revised) for employees’ . . . use in obtaining medical certification").
Form WH-380 includes an attachment identifying, in language that paral-
lels the regulations, the categories of serious health conditions. Although
the record does not contain the corresponding attachment for AT&T’s
FMLA-2, there appears to be no dispute that the categories are the same
as those on the WH-380.
   5
     The record does not reveal whether this serious discussion was pre-
ceded by a development session.
8                   MILLER v. AT&T CORPORATION
gar had a second serious discussion with Miller regarding her atten-
dance on October 31, 1995. After Miller incurred additional
chargeable absences on December 4, 1995 and January 3 and 4, 1996,
AT&T issued a letter of warning. The letter informed Miller that her
attendance was unsatisfactory and that she could be subject to further
disciplinary action, including dismissal, if her attendance did not
improve.

   In spite of this warning, Miller incurred three more chargeable
absences in March and April 1996. However, rather than proceeding
to the next step in the disciplinary process and issuing Miller a final
letter of warning, AT&T reissued the previous letter of warning. Mil-
ler incurred yet more chargeable absences on May 16 and June 17. As
a result, AT&T issued Miller a final letter of warning on June 25,
1996. The letter specifically warned Miller that her next chargeable
absence could result in dismissal.

   On August 27, AT&T advised Miller that the final letter of warning
would be rescinded if she had perfect attendance through December
27 and that the letter of warning would be rescinded if she had perfect
attendance through March 27, 1997. Nevertheless, Miller incurred a
chargeable absence on December 19. Miller was not discharged for
this absence, but the final letter of warning remained in effect.

   On December 26, 1996, Miller began feeling ill while at work. She
completed her shift that day but was too ill to work on the 27th. The
following day, Miller sought treatment at an urgent care center. Dr.
T. Donald Sommerville diagnosed Miller as suffering from the flu
and determined that she was severely dehydrated. He also conducted
a blood test, which revealed that Miller’s white blood cell and platelet
counts were significantly lower than normal. After administering
intravenous fluids, Dr. Sommerville directed Miller to take over-the-
counter medications to alleviate her symptoms and to return on
December 30 for reevaluation. On December 30, Dr. Sommerville
examined Miller and conducted another blood test, which revealed
that Miller’s white blood cell and platelet counts were still low,
although the platelet level had improved and Miller felt better. After
consulting a hematologist, Dr. Sommerville directed Miller to return
two weeks later for a third blood test. By the time of the third test,
Miller’s white blood cell and platelet counts had returned to normal.
                      MILLER v. AT&T CORPORATION                            9
   At the conclusion of her initial visit on December 28, Miller was
given a work-excuse slip for December 28 through the 31st. On
December 31, Miller telephoned the urgent care center and requested
a work-excuse slip for January 1, explaining that she was feeling bet-
ter but needed an additional day off work. The urgent care center
granted this request.

   Miller subsequently requested FMLA leave for December 27
through January 1. In response to item 3 on the FMLA-2,
Dr. Sommerville checked category II, indicating that Miller suffered
a period of incapacity of at least three consecutive calendar days
involving treatment two or more times.6 The next item on the form,
item 4, provided:

      To Be Completed only for a "serious health condition" of an
      employee’s spouse, child, or parent: Describe the medical
      facts which support your certification, including a brief
      statement as to how the medical facts meet the criteria of
      one of these categories.

J.A. 345.7 Although Dr. Sommerville was not required to respond to
item 4 because Miller herself was the patient, he nevertheless wrote
"Influenza type ‘A’ (See Attached Statement)." Id. Attached to the
FMLA-2 were copies of a bill indicating the treatment Miller received
on December 28 and a sheet of instructions to Miller. The instruction
  6
     Category II also applies to periods of incapacity accompanied by a
single visit to a health care provider that results in a regimen of continu-
ing treatment. Dr. Sommerville’s instructions to Miller to rest, take over-
the-counter medications, and increase her fluid intake did not constitute
a regimen of continuing treatment. See 29 C.F.R. § 825.114(b) (explain-
ing that "the taking of over-the-counter medications such as aspirin, anti-
histamines, or salves; or bedrest, drinking fluids, exercise, and other
similar activities that can be initiated without a visit to a health care pro-
vider is not, by itself, sufficient to constitute a regimen of continuing
treatment for purposes of FMLA leave").
   7
     As noted previously, see supra note 4, AT&T’s FMLA-2 is based
upon, and is very similar to, Form WH-380 promulgated by the Secretary
of Labor. However, item 4 on Form WH-380 is not limited to serious
health conditions suffered by an employee’s spouse, child, or parent.
10                  MILLER v. AT&T CORPORATION
sheet included the notation, "Recheck in 2 days, sooner or to ER if
worse." Id. at 348.

   AT&T denied Miller’s request for FMLA leave on February 26,
1997. Maxine M. Condie, RN, a division manager with the Health
Affairs Office, determined that Miller’s illness was not covered by the
FMLA because (1) the flu is not generally considered to be the type
of condition for which an employee is entitled to FMLA leave; and
(2) the information submitted by Miller did not demonstrate that she
received treatment on two or more occasions.

   On March 12, Attendance Administrator Kathy Collison learned
that Miller’s FMLA request had been denied. Collison reviewed Mil-
ler’s attendance record and concluded that Miller should be termi-
nated for excessive absenteeism. In connection with this review,
Collison consulted Joan O’Hara of the Health Affairs Office, who
informed Collison that any attempt by Miller to reopen the denial of
the leave request would be unsuccessful. Collison recommended ter-
mination to Miller’s immediate supervisor, Nan Hensley. After
reviewing Miller’s attendance record and consulting with various oth-
ers, including Snedegar, Hensley decided to fire Miller. Miller was
terminated on March 20, 1997.

                                   2.

   At the time of Miller’s termination, she had two additional
absences, on January 21 and January 31. Miller was absent on Janu-
ary 21 so that she could take her husband to an appointment with an
eye doctor. On January 27, Miller applied for intermittent FMLA
leave to transport her husband to and from appointments related to his
vision problems. See 29 U.S.C.A. § 2612(b)(1). In connection with its
evaluation of the request, AT&T contacted Mr. Miller’s physician,
who provided a list of dates on which he had seen Mr. Miller.
Because January 21 was not among the listed dates, the Health Affairs
Office denied FMLA coverage for this absence. During discovery in
this litigation, however, another physician submitted an affidavit stat-
ing that he had examined Mr. Miller on January 21 and had dilated
Mr. Miller’s eyes, making it impossible for him to drive home.

  Miller was absent on January 31 due to side effects of an injection
she received on January 30 to treat a chronic medical condition. On
                     MILLER v. AT&T CORPORATION                        11
February 3, Miller requested intermittent leave to receive three
injections—including the one she had received on January 30—and
for a follow up visit. Miller’s request form also noted that she "may
also miss work because of pain from" her condition. J.A. 729. The
Health Affairs Office granted Miller four days of intermittent FMLA
leave—one day for each injection plus one day for a follow-up
appointment. The Health Affairs Office did not grant Miller FMLA
leave for her absence on January 31.

   AT&T’s Health Affairs Office denied Miller’s FMLA leave
requests for the January 21 and 31 absence on or about May 29, 1997.
Had Miller not already been terminated based upon the December 27-
January 1 absence, AT&T would have terminated her employment for
the absences on January 21 and 31.

                                    3.

   Following her termination, Miller unsuccessfully sought full-time
employment with several companies. In August 1997, after seeking
employment for five months, she enrolled as a full-time student at the
West Virginia University Institute of Technology, where she trained
for a position as an operating room technician. From July 1998 to Jan-
uary 1999, Miller worked six to 12 hours per week at a restaurant. On
August 1, 1999, Miller began full-time employment as an operating
room technician. In this position, Miller earns approximately $30 less
per day than she did at AT&T.

                        D. Procedural History

   Miller filed this action in August 1998, alleging, as is relevant here,
that AT&T violated her rights under the FMLA by denying her
request for FMLA leave for the December 27-January 1 absences.
Following discovery, the district court granted summary judgment to
Miller on the issue of liability, holding that Miller’s flu constituted a
serious health condition and that she had provided adequate certifica-
tion of her need for FMLA leave. See Miller v. AT&T, 60 F. Supp.
2d 574, 579-80 (S.D. W. Va. 1999) [hereinafter Miller I]. The ques-
tion of the appropriate remedy was submitted to the district court on
stipulated facts. The court held that Miller was entitled to back pay,
12                   MILLER v. AT&T CORPORATION
plus interest, from the date of her termination to the date of the order.8
See Miller v. AT&T, 83 F. Supp. 2d 700, 709 (S.D. W. Va. 2000)
[hereinafter Miller II].

                                   II.

   We first consider AT&T’s challenge to the grant of summary judg-
ment on the question of liability. AT&T attacks the ruling on three
fronts. First, AT&T contends that the flu, or at least the flu from
which Miller suffered, is not a "serious health condition" within the
meaning of the Act and regulations. Alternatively, AT&T argues that
to the extent that Miller’s flu met the regulatory criteria for a serious
health condition, those criteria are invalid as contrary to Congress’
intent in enacting the FMLA. Finally, AT&T contends that it properly
denied Miller’s request for FMLA leave because the certification she
submitted in support of the request was inadequate. We review the
grant of summary judgment de novo, and we must affirm if the undis-
puted facts establish that Miller was entitled to judgment as a matter
of law. See Wadkins v. Arnold, 214 F.3d 535, 538 (4th Cir.), cert.
denied, 121 S. Ct. 485 (2000).

                                   A.

   We turn first to AT&T’s contention that Miller’s flu was not a "se-
rious health condition" under the Act and regulations. First, AT&T
contends that Miller cannot satisfy the regulatory criteria for a serious
health condition because she did not receive "treatment" on two or
more occasions.9 Failing this, AT&T argues that even if Miller quali-
fied for FMLA leave under the regulatory criteria for "continuing
treatment," the regulations specifically exclude the flu from FMLA
coverage. We address these claims seriatim.
  8
     The district court also ordered AT&T to offer Miller reinstatement,
which she declined. The court denied Miller’s requests for front pay and
liquidated damages. These portions of the order of the district court are
not before us.
   9
     AT&T does not dispute that Miller was an eligible employee or that
Miller was incapacitated for three or more consecutive days.
                      MILLER v. AT&T CORPORATION                            13
   We begin with AT&T’s contention that Miller did not receive treat-
ment from Dr. Sommerville on two or more occasions. AT&T asserts
that Miller’s second visit to Dr. Sommerville—during which he con-
ducted a physical examination and drew blood—did not constitute
"treatment" because Dr. Sommerville simply evaluated Miller’s con-
dition. However, this assertion is contradicted by the regulations,
which define "treatment" to include "examinations to determine if a
serious health condition exists and evaluations of the condition." 29
C.F.R. § 825.114(b). Under this definition, Miller’s second visit to
Dr. Sommerville clearly constituted "treatment."

   AT&T next argues that even if Miller satisfies the regulatory
criteria for a "serious health condition," the regulations nevertheless
specifically exclude the flu and other minor illnesses from coverage
under the FMLA. AT&T points to the following regulatory language:

       Ordinarily, unless complications arise, the common cold, the
       flu, ear aches, upset stomach, minor ulcers, headaches other
       than migraine, routine dental or orthodontia problems, peri-
       odontal disease, etc., are examples of conditions that do not
       meet the definition of a serious health condition and do not
       qualify for FMLA leave.

29 C.F.R. § 825.114(c) (2000) (emphasis added). According to
AT&T, this regulation establishes that absent complications, the flu
is never a serious health condition even if the regulatory test is satisfied.10
See Brannon v. Oshkosh B’Gosh, Inc., 897 F. Supp. 1028, 1036 n.8
(M.D. Tenn. 1995) ("Although the flu patient may pass the [regula-
tory] test, flu is specifically excluded from coverage" under the
FMLA.). We disagree.

  10
    AT&T also maintains that Miller did not suffer any "complications"
from the flu. Miller argues that her severe dehydration and lowered white
blood cell and platelet counts constituted complications within the mean-
ing of the regulation. In light of our conclusion that § 825.114(c) does
not preclude FMLA coverage of an episode of the flu when the regula-
tory definition of a serious health condition is satisfied, we need not
decide whether Miller suffered from any complications.
14                  MILLER v. AT&T CORPORATION
   There is unquestionably some tension between subsection (a), set-
ting forth objective criteria for determining whether a serious health
condition exists, and subsection (c), which states that certain enumer-
ated conditions "ordinarily" are not serious health conditions. Indeed,
that tension is evidenced by Miller’s illness. Miller was incapacitated
for more than three consecutive calendar days and received treatment
two or more times; thus, she satisfied the regulatory definition of a
serious health condition under subsection (a). But, the condition from
which Miller suffered—the flu—is one of those listed as being "ordi-
narily" not subject to coverage under the FMLA. AT&T urges us to
resolve this tension by holding that subsection (c) essentially excepts
the enumerated ailments from FMLA coverage even when an individ-
ual suffering from one of those ailments satisfies the regulatory
criteria of subsection (a).

  Miller, in contrast, urges us to defer to the position taken by the
Secretary of Labor in a 1996 opinion letter:

        The FMLA regulations . . . provide examples, in section
     825.114(c), of conditions that ordinarily, unless complica-
     tions arise, would not meet the regulatory definition of a
     serious health condition and would not, therefore, qualify
     for FMLA leave . . . . Ordinarily, these health conditions
     would not meet the [regulatory criteria] . . . . If, however,
     any of these conditions met the regulatory criteria for a seri-
     ous health condition, . . . then the absence would be pro-
     tected by the FMLA.

        . . . Complications, per se, need not be present to qualify
     as a serious health condition if the regulatory . . . tests are
     otherwise met. The regulations reflect the view that, ordinar-
     ily, conditions like the common cold and flu (etc.) would not
     be expected to meet the regulatory tests, not that such condi-
     tions could not routinely qualify under FMLA where the
     tests are, in fact, met in particular cases.

Opinion Letter FMLA-86, 1996 WL 1044783 (Dec. 12, 1996). The
1996 letter superseded a previous opinion letter ("the 1995 letter")
that concluded that meeting the regulatory criteria "‘does not convert
minor illnesses such as the common cold into serious health condi-
                     MILLER v. AT&T CORPORATION                           15
tions in the ordinary case (absent complications).’" Thorson v. Gem-
ini, Inc., 205 F.3d 370, 378 (8th Cir.) (quoting Opinion Letter FMLA-
57 (Apr. 7, 1995)), cert. denied, 121 S. Ct. 172 (2000). In the 1996
letter, the Department of Labor stated that "[u]pon further review of
this issue . . . , we have determined that [the 1995] letter expresses
an incorrect view, being inconsistent with the Department’s estab-
lished interpretation of qualifying ‘serious health conditions’ under
the FMLA regulations." Opinion Letter FMLA-86.

   Agency interpretations that are contained in opinion letters "are
entitled to respect . . . , but only to the extent that those interpretations
have the power to persuade." Christensen v. Harris County, 529 U.S.
576, 587 (2000) (internal quotation marks omitted); cf. Flood v. New
Hanover County, 125 F.3d 249, 253 (4th Cir. 1997) (explaining that
while letter ruling is not binding, "it does constitute a body of experi-
enced and informed judgment, and we give it substantial weight"
(internal quotation marks omitted)). However, "an agency’s interpre-
tation of a statute or regulation that conflicts with a prior interpreta-
tion is entitled to considerably less deference than a consistently held
agency view." Thomas Jefferson Univ. v. Shalala, 512 U.S. 504, 515
(1994) (internal quotation marks omitted). AT&T argues that the
1996 letter is not persuasive in light of its inconsistency with the 1995
letter.

   Even without deferring to the 1996 letter, we nevertheless conclude
that § 825.114(c) is properly interpreted as indicating merely that
common ailments such as the flu normally will not qualify for FMLA
leave because they generally will not satisfy the regulatory criteria for
a serious health condition. See Thorson, 205 F.3d at 379 (adopting
this interpretation of the regulations without deferring to 1996 letter).
Whenever possible, this court must reconcile apparently conflicting
provisions. See Chem. Weapons Working Group, Inc. v. United States
Dep’t of the Army, 111 F.3d 1485, 1490 (10th Cir. 1997). That is not
difficult to do here. 29 C.F.R. § 825.114(c) provides that "ordinarily"
the flu will not qualify as a serious health condition. Presumably, this
is because the flu (and the other conditions listed in the regulation)
ordinarily will not meet the objective criteria for a serious health con-
dition, inasmuch as such an illness normally does not result in an
inability to work for three or more consecutive calendar days or does
not require continuing treatment by a health care provider. Sec-
16                  MILLER v. AT&T CORPORATION
tion 825.114(c) simply does not automatically exclude the flu from
coverage under the FMLA. Rather, the provision is best read as clari-
fying that some common illnesses will not ordinarily meet the regula-
tory criteria and thus will not be covered under the FMLA.11

                                   B.

   AT&T’s next challenge to liability concerns the validity of the reg-
ulations themselves. The company argues that if Miller’s flu was a
serious health condition pursuant to the regulations, those regulations
are invalid as contrary to congressional intent. AT&T primarily
attacks the regulatory definition of "treatment," maintaining that a
mere evaluation of a patient’s condition should not qualify as treat-
ment. However, AT&T also makes a more general challenge to the
regulations, maintaining that Congress did not intend for the FMLA
to cover relatively minor illnesses such as the flu.

   In enacting the FMLA, Congress explicitly granted the Secretary
of Labor authority to promulgate regulations implementing the Act.
See 29 U.S.C.A. § 2654. Regulations promulgated pursuant to such an
express delegation of authority "are given controlling weight unless
they are arbitrary, capricious, or manifestly contrary to the statute."
Chevron U.S.A. Inc. v. Natural Res. Def. Council, Inc., 467 U.S. 837,
844 (1984). Particularly when a regulatory choice "represents a rea-
sonable accommodation of conflicting policies that were committed
to the agency’s care by the statute, we should not disturb it unless it
appears from the statute or its legislative history that the accommoda-
tion is not one that Congress would have sanctioned." Id. at 845
(internal quotation marks omitted). Moreover, so long as the regula-
tions promulgated by the Secretary are reasonable, we are not at lib-
erty to question their wisdom. See Nat’l Rifle Ass’n of Am. v. Reno,
216 F.3d 122, 132 (D.C. Cir. 2000), petition for cert. filed, ___
U.S.L.W. ___ (U.S. Feb. 22, 2001) (No. 00-1332). We must bear in
mind, however, that "[t]he rulemaking power granted to an adminis-
trative agency charged with the administration of a federal statute is
not the power to make law. Rather, it is the power to adopt regula-
tions to carry into effect the will of Congress as expressed by the stat-
  11
   This is the position taken by the Secretary of Labor, who filed an
amicus brief and participated in oral argument.
                    MILLER v. AT&T CORPORATION                        17
ute." Ernst & Ernst v. Hochfelder, 425 U.S. 185, 213-14 (1976)
(internal quotation marks omitted). Deference to administrative poli-
cymaking is not so great as to reduce our role to rubber-stamping reg-
ulations that are "inconsistent with a statutory mandate or that
frustrate the congressional policy underlying a statute." NLRB v.
Brown, 380 U.S. 278, 291 (1965). If the Secretary’s regulations
implementing the FMLA subvert congressional intent to a degree that
renders the regulations arbitrary, we are obliged to declare them
inconsistent with the statute. See Chevron U.S.A., 467 U.S. at 843 n.9
("The judiciary is the final authority on issues of statutory construc-
tion and must reject administrative constructions which are contrary
to clear congressional intent.").

   Congress enacted the FMLA in response to concern regarding,
inter alia, "inadequate job security for employees who have serious
health conditions that prevent them from working for temporary peri-
ods." 29 U.S.C.A. § 2601(a)(4); see S. Rep. No. 103-3, at 11-12,
reprinted in 1993 U.S.C.C.A.N. 3, 13-14 (noting that "[j]ob loss
because of illness has a particularly devastating effect on workers
who support themselves and on families where two incomes are nec-
essary to make ends meet or where a single parent heads the house-
hold"). Congress did not intend to create a federal sick leave program
but rather aspired to create a workable "minimum labor standard for
leave" that would balance the needs of employees and the interests of
employers. S. Rep. No. 103-3, at 4, reprinted in 1993 U.S.C.C.A.N.
at 6; see id. at 4-5, reprinted in 1993 U.S.C.C.A.N. at 6-7; see also
Hukill v. Auto Care, Inc., 192 F.3d 437, 441 (4th Cir. 1999) ("The
purpose of the FMLA is to balance the demands of the workplace
with the needs of employees to take leave for eligible medical condi-
tions and compelling family reasons."), cert. denied, 120 S. Ct. 1978
(2000).

   We first consider AT&T’s contention that the regulatory definition
of "treatment" is overly broad because it includes mere evaluations of
an employee’s condition. Nothing in the legislative history discusses
the "continuing treatment" requirement, and Congress elected not to
provide a statutory definition of that term.12 There is thus nothing
  12
    The dissent contends that "the word ‘treatment’ is clear and unam-
biguous in and of itself," infra at 28, and does not include mere evalua-
18                   MILLER v. AT&T CORPORATION
upon which to base a conclusion that the regulatory definition of
treatment, which allows for situations in which a health care provider
determines that an illness requires continued monitoring but not
aggressive treatment, is contrary to congressional intent. Cf. S. Rep.
No. 103-3, at 29, reprinted in 1993 U.S.C.C.A.N. at 31 (noting that
serious health conditions typically "involve either inpatient care or
continuing treatment or supervision by a health care provider, and fre-
quently involve both" (emphasis added)).

   We note also that AT&T’s challenge to the regulatory definition of
"treatment" overlooks the fact that the "treatment" requirement does
not stand alone. Consistent with the statutory language, the regula-
tions require that treatment be accompanied by a period of incapacity
of at least three consecutive days. It is apparent that the requirement
that the employee be incapacitated will suffice to weed out those
claims that are based on nothing more than multiple visits to a physi-
cian for a minor health complaint.

   We next consider AT&T’s more general argument that, to the
extent the regulations permit FMLA coverage for the flu and similar
illnesses, those regulations contravene the legislative purpose under-
lying the FMLA. In support of this claim, AT&T points to the follow-
ing passage from the Senate Report:

       The term "serious health condition" is not intended to
     cover short-term conditions for which treatment and recov-
     ery are very brief. It is expected that such conditions will fall
     within even the most modest sick leave policies. Conditions
     or medical procedures that would not normally be covered
     by the legislation include minor illnesses which last only a
     few days and surgical procedures which typically do not
     involve hospitalization and require only a brief recovery
     period. Complications arising out of such procedures that

tions of a condition. We fail to see, however, how the cited definition of
"treatment"—"the systemic effort to cure illness and relieve symptoms,
as with medicines, surgery, etc.," id. (internal quotation marks omitted)
—necessarily excludes determination of the appropriate course of treat-
ment (i.e., diagnosis) or periodic evaluations of a patient’s condition to
determine whether the chosen course of treatment is proving effective.
                    MILLER v. AT&T CORPORATION                        19
    develop into "serious health conditions" will be covered by
    the act. . . .

       Examples of serious health conditions include but are not
    limited to heart attacks, heart conditions requiring heart
    bypass of [sic] valve operations, most cancers, back condi-
    tions requiring extensive therapy or surgical procedures,
    strokes, severe respiratory conditions, spinal injuries, appen-
    dicitis, pneumonia, emphysema, severe arthritis, severe ner-
    vous disorders, injuries caused by serious accidents on or off
    the job, ongoing pregnancy, miscarriages, complications or
    illnesses related to pregnancy, such as severe morning sick-
    ness, the need for prenatal care, childbirth and recovery
    from childbirth. All of these conditions meet the general test
    that either the underlying health condition or the treatment
    for it requires that the employee be absent from work on a
    recurring basis or for more than a few days for treatment or
    recovery. They also involve either inpatient care or continu-
    ing treatment or supervision by a health care provider, and
    frequently involve both.

S. Rep. No. 103-3, at 28-29, reprinted in 1993 U.S.C.C.A.N. at 30-31
(emphasis added); see Bauer v. Dayton-Walther Corp., 910 F. Supp.
306, 310 (E.D. Ky. 1996) ("Congress sought to parse out illnesses
which it believed should be treated under sick leave policy from those
much more serious illnesses that implicate the protections of the
FMLA."), aff’d, 118 F.3d 1109 (6th Cir. 1997).

   AT&T is correct, of course, that the legislative history indicates
that in enacting the FMLA Congress was focused on "major" ill-
nesses, such as cancer, rather than relatively minor ailments. But, the
passage in the Senate Report on which AT&T relies is not reflected
in the statutory language. See Thorson, 205 F.3d at 380. Rather, the
FMLA defines "serious health condition" broadly "and does not
include any examples of conditions that either do or do not qualify as
FMLA ‘serious health conditions.’" Id. Consistent with the statutory
language, the regulations promulgated by the Secretary of Labor
establish a definition of "serious health condition" that focuses on the
effect of an illness on the employee and the extent of necessary treat-
ment rather than on the particular diagnosis. This policy decision is
20                  MILLER v. AT&T CORPORATION
neither unreasonable nor manifestly inconsistent with Congress’
intent to cover illnesses that "require[ ] that the employee be absent
from work on a recurring basis or for more than a few days for treat-
ment or recovery" and involve "continuing treatment or supervision
by a health care provider." S. Rep. No. 103-3, at 29, reprinted in 1993
U.S.C.C.A.N. at 31. It is possible, of course, that the definition
adopted by the Secretary will, in some cases—and perhaps even in
this one—provide FMLA coverage to illnesses that Congress never
envisioned would be protected. We cannot say, however, that the reg-
ulations adopted by the Secretary are so manifestly contrary to con-
gressional intent as to be considered arbitrary. See Thorson, 205 F.3d
at 380.

                                  C.

   Finally, AT&T contends that the documentation submitted by Mil-
ler in support of her request for FMLA leave was inadequate because
it did not indicate that she had received treatment two or more times.
As noted above, Dr. Sommerville checked Category II on the FMLA-
2, indicating that Miller had suffered a period of incapacity of three
or more days and had received treatment two or more times. Addi-
tionally, Miller submitted a copy of an instruction sheet indicating
that she was to return to the urgent care center in two days for a fol-
low up visit. As we understand AT&T’s argument, it contends that
Miller’s submission would have been adequate if either (1) Dr. Som-
merville had specifically stated, in response to item 4 on the FMLA-
2, that he treated Miller two or more times; or (2) Miller had submit-
ted some record of her second visit to Dr. Sommerville.

   Both of these assertions attempt to take Miller to task for failing
to provide information that AT&T did not request, and accordingly
we reject them. First, by its terms the FMLA-2 only required Dr.
Sommerville to check the appropriate category under item 3, which
he undisputably did. AT&T nevertheless maintains that because
Dr. Sommerville did not specify, in response to item 4, that he had
treated Miller two or more times, the certification was inadequate on
its face. However, Dr. Sommerville was not required to provide an
answer to item 4 because that item specified that it was to be com-
pleted "only for a ‘serious health condition’ of an employee’s spouse,
child, or parent." J.A. 345 (emphasis omitted). Any failure by Dr.
                    MILLER v. AT&T CORPORATION                        21
Sommerville to provide information under item 4 is not an appropri-
ate basis for the denial of Miller’s request for FMLA leave. Similarly,
nothing on the FMLA-2 required Miller to submit supporting docu-
mentation for her leave request. Under these circumstances, to deny
a leave request on the basis that supporting documentation was not
submitted would be unconscionable. Moreover, to the extent it
viewed Miller’s certification as incomplete, AT&T was required to
provide Miller a reasonable opportunity to cure any deficiency. See
29 C.F.R. § 825.305(d) (2000).13

   AT&T argues that a conclusion that the certification submitted by
Miller was adequate would "render[ ] the certification process mean-
ingless." Brief of Appellant at 30. We disagree. The FMLA allows
employers to require information regarding the "medical facts" sup-
porting a health care provider’s conclusion that the employee suffered
from a serious health condition. The salient point, however, is that
AT&T elected not to require such information on its certification
form.

                                  III.

   Having determined that the district court correctly found AT&T
liable for violating Miller’s rights under the FMLA, we turn to
AT&T’s challenges to the back pay award. The company first main-
tains that, pursuant to the after-acquired evidence doctrine, the award
should be limited to the period from Miller’s termination on March
20, 1997 to May 29, 1997, when the Health Affairs Office denied
Miller’s requests for FMLA leave for the January 21 and 31 absences.
Second, AT&T argues that Miller failed to mitigate her damages.
Although our reasoning differs from that of the district court with
respect to the after-acquired evidence claim, we nevertheless con-
  13
    The district court criticized AT&T for failing to follow the "second
opinion" procedures in the FMLA. See Miller I, 60 F. Supp. 2d at 580.
We agree with AT&T that a second opinion would have been of no use
here. AT&T never questioned Miller’s assertion that she had the flu or
that she was unable to work for the duration of her illness. Rather, AT&T
questioned whether Miller had received treatment on two or more occa-
sions and whether the flu was a FMLA-covered illness. A second medi-
cal opinion would not have shed light on either of these questions.
22                  MILLER v. AT&T CORPORATION
clude that Miller was entitled to the full amount of back pay awarded
by the district court.

   The question of the appropriate remedy was submitted to the dis-
trict court on facts to which the parties jointly stipulated. We are thus
presented only with questions of law, which are subject to de novo
review. See Ward v. Allied Van Lines, Inc., 231 F.3d 135, 138 (4th
Cir. 2000).

                                   A.

   AT&T maintains that the denial of FMLA leave for the January
absences constitutes after-acquired evidence under McKennon v.
Nashville Banner Publishing Co., 513 U.S. 352, 362-63 (1995) (hold-
ing that an award of back pay may be limited by subsequently
acquired evidence of employee wrongdoing that would have justified
the employee’s termination). The district court rejected this argument,
concluding that the after-acquired evidence doctrine was not available
to AT&T and, alternatively, that the doctrine should not limit Miller’s
back pay award because she was entitled to FMLA leave for the Janu-
ary absences. See Miller II, 83 F. Supp. 2d at 705-06. We agree with
AT&T that the after-acquired evidence doctrine applies to AT&T’s
claim that it would have terminated Miller for the January absences.
Nevertheless, we affirm the district court because AT&T failed to
meet its burden of establishing that Miller was not entitled to FMLA
leave for those absences.

   The after-acquired evidence doctrine concerns the effect of evi-
dence of employee misconduct acquired by the employer after the
employee has been terminated for a discriminatory reason. In McKen-
non, the Supreme Court held that evidence of employee wrongdoing
acquired after wrongful termination may limit an award of back pay
(and disentitle an employee to front pay and reinstatement) when the
employer establishes "that the wrongdoing was of such severity that
the employee in fact would have been terminated on those grounds
alone if the employer had known of it at the time of the discharge."
Id. at 362-63. The doctrine thus balances the need to enforce national
employment policy by deterring and punishing employer misconduct,
while taking "due account of the lawful prerogatives of the employer
                    MILLER v. AT&T CORPORATION                      23
in the usual course of its business and the corresponding equities that
it has arising from the employee’s wrongdoing." Id. at 361.

   The district court concluded that the after-acquired evidence doc-
trine did not apply to the January absences because "AT&T was
aware of Miller’s additional absences at the time of her termination"
and "therefore had the ability to evaluate that conduct as part of an
overall decision to terminate her employment." Miller II, 83 F. Supp.
2d at 705. This reasoning overlooks the fact that, while AT&T was
aware that the additional absences had occurred when it terminated
Miller, the Health Affairs Office had not yet determined whether
those absences were covered by the FMLA. AT&T policy therefore
prohibited it from considering those absences in deciding whether to
terminate Miller. Cf. 29 C.F.R. § 825.307(a)(2) (2000) (providing that
an employee is "provisionally entitled" to protection under the FMLA
while the employer seeks a second opinion).

   Perhaps recognizing this flaw in its logic, the district court noted
that AT&T should have resolved the ongoing investigation into the
additional absences before deciding to terminate Miller. See Miller II,
83 F. Supp. 2d at 705. Such a requirement is not realistic. Indeed, in
the case of a chronically absent employee, it is entirely possible that
evaluating all outstanding requests for FMLA leave before making a
decision would effectively preclude any action by the employer.

   Having determined that the after-acquired evidence doctrine
applies to the January absences, we now turn to the question of
whether AT&T could have terminated Miller for those absences, i.e.,
whether the absences were protected by the FMLA. The district court
concluded that Miller was entitled to FMLA leave for each absence,
and thus declined to limit Miller’s back pay award. See id. at 705-06.
AT&T argues that this conclusion is precluded by the parties’ stipula-
tion that AT&T would have terminated Miller for the January 21 and
31 absences had it not already terminated her. The stipulation on
which AT&T relies provides as follows:

    Because Miller’s absences on January 21 and 31, 1997,
    were determined by AT&T not to be covered by the FMLA
    and were deemed chargeable, those absences were a viola-
    tion of Miller’s final letter of warning. Since Miller would
24                  MILLER v. AT&T CORPORATION
     have remained under that final letter of warning, either or
     both of those absences would have resulted in Miller’s ter-
     mination if she had continued to be employed by AT&T at
     the time it was learned that they were in fact chargeable.

J.A. 706.

   AT&T reads too much into this stipulation. In order to limit the
award of back pay based upon the January absences, AT&T was
required to prove (1) that Miller was not entitled to FMLA leave for
the absences, and (2) that AT&T would in fact have terminated Miller
based on the absences. See McKennon, 513 U.S. at 362-63. Unques-
tionably, the stipulation establishes that AT&T would in fact have ter-
minated Miller for the January absences, thus satisfying the second
part of AT&T’s burden. However, the stipulation does not establish
that Miller was not entitled to FMLA leave for the January absences,
but rather only states that AT&T believed that the absences were not
covered by the FMLA. The stipulation thus does not meet AT&T’s
burden under the first prong of the after-acquired evidence doctrine.
And, since AT&T raises no other challenge to the conclusion of the
district court that Miller was entitled to FMLA leave for the January
absences, we affirm that ruling.

                                  B.

   AT&T also argues that the award of back pay should have been
limited by Miller’s failure to mitigate her damages. A plaintiff in an
employment discrimination case must mitigate damages by diligently
"seeking and accepting new employment substantially equivalent to
that from which he was discharged." Brady v. Thurston Motor Lines,
Inc., 753 F.2d 1269, 1273 (4th Cir. 1985). Failure to diligently seek
new employment precludes an award of back pay for the period dur-
ing which employment was not sought. See id. The duty to mitigate
is not without limits, however. For example, a plaintiff "need not go
into another line of work, accept a demotion, or take a demeaning
position." Ford Motor Co. v. EEOC, 458 U.S. 219, 231 (1982). The
defendant bears the burden of demonstrating that the plaintiff has
failed to fulfill the duty to mitigate. See Martin v. Cavalier Hotel
Corp., 48 F.3d 1343, 1358 (4th Cir. 1995).
                     MILLER v. AT&T CORPORATION                        25
   AT&T argues that Miller’s decision to forego her search for
employment and become a full-time student is inconsistent with the
duty to diligently seek new employment. The district court disagreed,
reasoning that a plaintiff who enrolls in school only after a diligent
but unsuccessful search for employment has not failed to mitigate
damages. See Miller II, 83 F. Supp. 2d at 707-08.

   We conclude that Miller did not fail to mitigate her damages.
"[T]he central question a court must consider when deciding whether
a student-claimant has mitigated her damages is whether an individu-
al’s furtherance of [her] education is inconsistent with [her] responsi-
bility to use reasonable diligence in finding other suitable
employment." Dailey v. Societe Generale, 108 F.3d 451, 456-57 (2d
Cir. 1997) (internal quotation marks omitted). Although AT&T cites
cases in which equitable relief was denied or limited on the basis that
the plaintiff had enrolled in school full-time, in each of these cases the
plaintiff sought to obtain greater future benefits by doing so. See, e.g.,
Floca v. Homcare Health Servs., Inc., 845 F.2d 108, 112-13 (5th Cir.
1988) (affirming denial of front pay to plaintiff who had left nursing
to enroll in law school); Miller v. Marsh, 766 F.2d 490, 492-93 (11th
Cir. 1985) (affirming denial of back pay to plaintiff who abandoned
temporary stenographer job in order to enroll in law school); Taylor
v. Safeway Stores, Inc., 524 F.2d 263, 267-68 (10th Cir. 1975)
(affirming limitation of back pay award to plaintiff who enrolled in
school full-time). The denial of back pay is arguably appropriate in
such cases. See Taylor, 524 F.2d at 268 ("[W]hen an employee opts
to attend school, curtailing present earning capacity in order to reap
greater future earnings, a back pay award for the period while attend-
ing school . . . would be like receiving a double benefit.").

   Here, in contrast, Miller enrolled in school only after a diligent but
fruitless search for employment. Moreover, the position for which
Miller trained while in school was not a "step up"—as an operating
room technician, Miller earns substantially less than she did at AT&T.
Miller thus did not "voluntarily absent[ ] herself from an active job
market because she believe[d] her ultimate earning potential [would]
be enhanced with the benefit of further education." Dailey, 108 F.3d
at 457; see id. at 456-58 (rejecting argument that plaintiff, who
enrolled in school after six-month job search was unsuccessful, had
failed to mitigate damages); Smith v. Am. Serv. Co. of Atlanta, Inc.,
26                  MILLER v. AT&T CORPORATION
796 F.2d 1430, 1432 (11th Cir. 1986) (holding that plaintiff who
enrolled in school after unsuccessfully seeking employment for seven
months, and who worked part-time while in school, did not fail to
mitigate damages); cf. Hanna v. Am. Motors Corp., 724 F.2d 1300,
1308-09 (7th Cir. 1984) (holding that plaintiff who had enrolled in
school, but who applied for and was willing to accept full-time
employment, had not failed to mitigate damages). We therefore affirm
the district court on this issue.

                                 IV.

   In sum, we conclude that AT&T violated Miller’s rights under the
FMLA when it denied her request for leave for the December 27-
January 1 absence. Miller’s flu satisfied the regulatory criteria for a
serious health condition, and, while we may question the wisdom of
regulations that arguably extend the scope of FMLA coverage beyond
what Congress envisioned, we cannot say that the regulations are
arbitrary. Additionally, we decline to hold that Miller’s certification
that she suffered from a serious health condition was inadequate
because it failed to include information that AT&T did not request.
Finally, we affirm the award of back pay, concluding that the award
should not be limited by the after-acquired evidence doctrine or by
any failure of Miller to mitigate her damages.

                                                          AFFIRMED

HILTON, Chief District Judge, dissenting:

   I believe the Secretary of Labor exceeded the scope of her dele-
gated authority in promulgating regulations under the Family and
Medical Leave Act ("FMLA"), 29 U.S.C. § 2601 et seq., that
expanded the expressed limits of the statute. In so doing, the Secre-
tary contradicted the express will of the Congress. Because I find that
the Secretary’s regulation that defines "continuing treatment" violates
Chevron, U.S.A., Inc. v. Natural Resources Defense Council, Inc., 467
U.S. 837 (1984), and is unconstitutional, I would reverse and order
that judgment be entered for AT&T. I respectfully dissent.

   The Constitution delegates to Congress alone "[a]ll legislative
[p]owers." U.S. Const. art. I, § 1. Congress alone makes the law
                    MILLER v. AT&T CORPORATION                        27
which the Executive enforces under Article II of the Constitution.
Congress cannot delegate its legislative power. See Whitman v. Amer-
ican Trucking Associations, 121 S. Ct. 903, 912 (2001); Loving v.
United States, 517 U.S. 748, 771 (1996); J.W. Hampton, Jr., & Co.
v. United States, 276 U.S. 394, 409 (1928). Out of these bedrock sep-
aration of powers principles, the Supreme Court has carved a limited
exception for an administrative agency to elucidate or explain a provi-
sion of a statute that it executes provided Congress gives the agency
such authority and gives it intelligible principles to guide its rulemak-
ing. See Whitman, 121 S. Ct. at 912; Chevron, 467 U.S. at 842. A del-
egation of rulemaking authority is arguably the exercise of legislative
power, the difference between legislative power and permissible
administrative regulation being a very fine line. See, e.g., Whitman,
121 S. Ct. at 920 (Thomas, J., concurring); Whitman, 121 S. Ct. at
920 (Stevens, J., concurring).

   When an agency engages in rulemaking, it must do so carefully
because of the delicate constitutional authority upon which such rule-
making rests and because of the scrutiny that courts will bring to bear
on such exercises of raw, sweeping power by unelected and unac-
countable officials. See Chevron, 467 U.S. at 843 n.9 ("The judiciary
is the final authority on issues of statutory construction."). Accord-
ingly, the Supreme Court has fashioned a two part test for a court to
apply when it reviews an agency’s construction of a statute which the
agency administers. See id. at 842-43. First, if Congress’ intent is
express and unambiguous, it must be given effect both by the courts
as well as the agency in question. See id. However, if Congress has
not directly addressed the precise question at issue, the issue for the
court is whether the agency’s regulation is a permissible construction
of the statute. See id. at 843. In determining whether an agency’s
interpretation of a statute is a permissible one, the Court must give the
agency’s interpretation controlling weight "unless [it is] arbitrary,
capricious, or manifestly contrary to the statute." Id. at 844.

   Because legislative power is vested in Congress alone, see U.S.
Const. art. I, § 1; Whitman, 121 S. Ct. at 920 (Thomas, J., concur-
ring), we must look first and foremost to its express will in the plain
terms of the statute itself. The Act defines a "serious health condition"
as:
28                   MILLER v. AT&T CORPORATION
      an illness, injury, impairment, or physical or mental condi-
      tion that involves—

       (A) inpatient care in a hospital, hospice, or residential
      medical care facility; or

        (B) continuing treatment by a health care provider.

29 U.S.C. § 2611(11). At issue here is the definition of "continuing
treatment." The Secretary promulgated a regulation that defined "con-
tinuing treatment" as including diagnosis and monitoring of a condi-
tion. See 29 C.F.R. § 825.114(b). She also promulgated a regulation
defining "continuing treatment" in such a way so as to include some
minor illnesses.1 See Maj. Op. at 19-20.

   The majority states that the legislative history provides no guidance
about what does or does not constitute "continuing treatment." See
Maj. Op. at 17. The majority also states that the statute does not
define "continuing treatment" any further and thus there is an absence
of expressed Congressional intent. See id. What the majority over-
looks, however, is the most persuasive expression of legislative intent
that exists: the plain meaning of the words of the statute itself. There
is no need—in fact, it is not permissible—to defer to an agency inter-
pretation of a statute when Congress has been express in the plain
terms of the statute itself. See Chevron, 467 U.S. at 842-43.

   The majority implicitly finds "continuing treatment" to be ambigu-
ous or else it would not have deferred to the agency’s interpretation.
I do not find "continuing treatment" to be ambiguous at all. I find per-
suasive AT&T’s argument that the word "treatment" is clear and
unambiguous in and of itself. In the medical context, it means "the
systematic effort to cure illness and relieve symptoms, as with medi-
cines, surgery, etc.," Random House College Dictionary 1400 (rev.
ed. 1980), or "management in the application of remedies; medical or
surgical application or service," 18 Oxford English Dictionary 464
  1
   These rules were promulgated by authority of 29 U.S.C. § 2654: "The
Secretary of Labor shall prescribe such regulations as are necessary to
carry out subchapter I of this chapter and this subchapter not later than
120 days after February 5, 1993."
                     MILLER v. AT&T CORPORATION                         29
(2d ed. 1989) (emphasis added). It is different from "diagnosis" which
means "the process of determining by examination the nature and cir-
cumstances of a diseased condition," Random House College Dictio-
nary 366 (rev. ed. 1980), or "determination of the nature of a diseased
condition; identification of a disease by careful investigation of its
symptoms and history," 4 Oxford English Dictionary 596 (2d ed.
1989). It is also different from mere monitoring or supervision of a
condition. See 9 Oxford English Dictionary 1002 (2d ed. 1989) (mon-
itoring means "to observe, supervise, or keep under review; to mea-
sure or test at intervals"); 17 Oxford English Dictionary 245 (2d ed.
1989) (supervision means "general management, direction, or control;
oversight, superintendence"). It is elementary that in medicine, first,
a physician diagnoses a condition and then, second, he treats that con-
dition. The definition of one is not subsumed within the other. The
fact is that they are different terms with different, plain meanings.

   The majority recognizes that "treatment" does not mean "diagno-
sis" or "monitoring" and vice versa when it states,

      There is thus nothing upon which to base a conclusion that
      the regulatory definition of treatment, which allows for situ-
      ations in which a health care provider determines that an ill-
      ness requires continued monitoring but not aggressive
      treatment, is contrary to congressional intent.

Maj. Op. at 17-18 (emphasis added). I believe the majority is incor-
rect: The statute is clear that treatment is required, not mere monitor-
ing. The majority recognizes that there is a difference between the
medical acts of diagnosis/monitoring and treatment, but chooses to
disregard the expressed will of the Congress that one be covered by
FMLA but not the other. We presume that Congress means what it
says when it writes laws. Had Congress intended to provide FMLA
leave for diagnosis and monitoring in addition to treatment, it would
have said so.2 Instead, it provided only for treatment. In 29 C.F.R.
  2
   In fact, a prior version of the bill, in defining "serious health condi-
tion," did provide for continuing treatment or continuous supervision. It
was later narrowed to provide only for continuing treatment. See 137
Cong. Rec. H9777 (daily ed. Nov. 13, 1991) (statement of Rep. Good-
ling) (discussing Gordon-Hyde Amendment).
30                   MILLER v. AT&T CORPORATION
§ 825.114(b), the Secretary expanded the definition of "continuing
treatment" to include diagnosis, supervision, or monitoring, in contra-
vention of the clear language of Congress. 29 C.F.R. § 825.114(b) is
therefore unconstitutional.3

   When 29 C.F.R. § 825.114, which defines "serious health condi-
tion," is viewed more broadly, it becomes even more apparent that the
Secretary’s rulemaking exceeded the limits of the statute. Under para-
graph (a), "serious health condition" is defined as either "inpatient
care," 29 C.F.R. § 825.114(a)(1), or "continuing treatment," 29 C.F.R.
§ 825.114(a)(2). The regulation defining "continuing treatment" in
turn provides two bases for coverage: treatment two or more times by
a health care provider, 29 C.F.R. § 825.114(a)(2)(i)(A), or treatment
by a health care provider on at least one occasion which results in a
"regimen of continuing treatment" under the supervision of a health
care provider, 29 C.F.R. § 825.114(a)(2)(i)(B).4 While Miller sought
coverage under the former, the latter prong demonstrates the internal
inconsistency and arbitrariness of the Secretary’s regulations. The
second prong is a circular definition. It defines "continuing treatment"
as requiring one visit to the doctor that is followed by . . . "continuing
treatment"! This strikes me as representative of the futile attempt by
the agency to define what is already a clear definition itself. "Serious
health condition" is defined, in part, as a condition requiring "continu-
ing treatment." It is downright bizarre to then define "continuing treat-
ment" (in the second prong) as requiring "continuing treatment." This
is indicative of the fact that "continuing treatment" means what it
says: treatment (not diagnosis, supervision, monitoring, etc.) on a
continuing basis. Both paragraphs (a) and (b), when read together,
therefore evince a consistent scheme by the Secretary to expand the
scope of FMLA coverage beyond what was intended by Congress.

   There is an additional basis upon which I would find the Secre-
tary’s regulations to be an unconstitutional exercise of agency rule-
making. It is undisputed that Miller had the ordinary, garden variety
  3
    This distinction is key in this case because Miller’s second visit to Dr.
Sommerville was, as the majority notes, see Maj. Op. at 13, for the pur-
pose of examination only.
  4
    Each, as the majority points out, requires proof of incapacity for three
days.
                     MILLER v. AT&T CORPORATION                        31
flu. Congress never intended the ordinary flu to be covered by FMLA
leave, as the majority acknowledges.5 See Maj. Op. at 18-20. Until
recently, the Department of Labor agreed that the flu was specifically
excepted from the FMLA. See Maj. Op. at 14-15. The question under
Chevron is of course not how we would interpret the statute de novo
but, rather, whether the agency interpreted the statute in a permissible
manner. Despite Congress’ intent not to cover the ordinary flu, the
majority acknowledges that the Secretary’s "test" for "continuing
treatment" might lead the ordinary flu to be covered, as is the result
in this case. See Maj. Op. at 20. This, the majority claims, is not arbi-
trary. I disagree. Returning to first principles, the Secretary had the
authority to promulgate regulations to enforce the FMLA only. What
the Secretary did—and what the majority acknowledges she did—was
to expand the scope of the statute beyond that which was intended by
the Congress. The majority concedes this point explicitly:

      It is possible, of course, that the definition adopted by the
      Secretary will, in some cases—and perhaps even in this one
      —provide FMLA coverage to illnesses that Congress never
      envisioned would be protected.

Maj. Op. at 20. Expanding the coverage of the statute beyond what
Congress intended is not only "arbitrary, capricious, [and] manifestly
contrary to the statute," Chevron, 467 U.S. at 844, but it is also a usur-
pation of legislative power, in violation of Article I of the Constitu-
tion. In short, it was arbitrary and capricious for the agency not to
create a minor illness exception when it made the regulations in ques-
tion and to expand the protection of the FMLA beyond what was
intended by Congress.

  Unelected, and therefore unaccountable, agency officials do not
  5
   Since the majority has ably reviewed the extensive legislative history
indicating Congress’ intent in this regard, I will not repeat it here. I
would only add that there were a number of floor statements in which
Congressmen stated their understanding that the flu and other minor ill-
nesses were not to be covered by the FMLA. See, e.g., 137 Cong. Rec.
H9727-28 (daily ed. Nov. 13, 1991) (statement of Rep. Roukema)
("sniffles or the flu" are not covered under the FMLA because they are
not serious conditions).
32                    MILLER v. AT&T CORPORATION
have the constitutional right or power to make law. See U.S. Const.
art. I, § 1; Chevron; Whitman. By contradicting the express will of
Congress, what the Secretary did here was to make law, not enforce
it. The Secretary’s regulations as they relate to "continuing treatment"
are unconstitutional usurpations of Congressional power and should
be found unconstitutional under the Chevron doctrine either because
they are contrary to the plain terms of the statute or because the Sec-
retary’s regulations are impermissible constructions of the statute.
Accordingly, I would reverse the district court and direct it to enter
judgment for AT&T. This would moot the issues of after-acquired
evidence and mitigation. It follows that I would grant AT&T’s motion
for attorneys’ fees.

     For these reasons, I respectfully dissent.
