              IN THE SUPREME COURT OF IOWA
                              No. 14–2062

                        Filed December 18, 2015


BRUCE BAKER,

      Appellee,

vs.

BRIDGESTONE/FIRESTONE and OLD REPUBLIC INSURANCE,

      Appellants.


      Appeal from the Iowa District Court for Polk County, Scott D.

Rosenberg, Judge.



      An employer appeals the district court’s ruling on judicial review of

the workers’ compensation commissioner, contending the employee’s

claim is time-barred because the discovery rule does not apply to work-

related injuries arising out of a singular event. AFFIRMED.



      Joseph M. Barron and William Timothy Wegman of Peddicord,
Wharton, Spencer, Hook, Barron & Wegman, LLP, West Des Moines, for

appellants.



      Martin Ozga of Neifert, Byrne & Ozga, P.C., West Des Moines, for

appellee.
                                              2

HECHT, Justice.

        An employee of a tire manufacturer strained his back on the job.

On the second anniversary of the incident, the manufacturer notified the

employee that the limitations period had expired and no further medical

services would be provided for treatment of the employee’s injury. The

employee filed a workers’ compensation proceeding within thirty days

after   receiving      the   notice    from       his   employer,   but   the   workers’

compensation commissioner concluded the statute of limitations barred

the claim.        We must decide in this case whether the commissioner

committed legal error in concluding the discovery rule does not apply

under the circumstances presented in this case. Because we conclude

the discovery rule can apply under the circumstances presented here, we

affirm the district court’s judgment reversing the agency’s decision.

        I. Background Facts and Proceedings.

        Bruce Baker works for Bridgestone/Firestone 1 at its Des Moines

plant. He has worked for the company since 1994. At the time of the

arbitration hearing in this case, he was a maintenance mechanic in the

hoist department.          As a maintenance mechanic, Baker inspected and

repaired machines located at the Bridgestone plant. This position often
required him to work on scissor lifts suspended up to twenty-six feet off

the ground. As a result, Baker frequently worked in awkward positions—

including reaching, leaning, and bending over backwards—to reach the

machines.

        On May 23, 2010, Baker sustained a back injury while working at

the plant. The accident occurred when he bent over to pick up a dropped

tool and inadvertently stepped on a lanyard hooked to his chest. When

        1For   economy’s sake, we refer to the company simply as Bridgestone.
                                      3

Baker attempted to stand up, the lanyard stuck under his right foot and

pulled him to the ground, causing him to roll over. He experienced pain

in his lower back and immediately reported the incident to a supervisor

as required by company policy. Baker resumed working after reporting

the incident.

      Dr. Troll, the plant physician, examined Baker on May 25.           The

doctor recommended stretching exercises and instructed Baker to use

acetaminophen and ice for his discomfort. Dr. Troll’s progress note for

the May 25 examination recommended Baker “work at his own pace

today.” Although he experienced some pain immediately after the fall,

Baker testified—and the commissioner found—that he did not foresee the

incident having a lasting impact on his ability to perform the functions of

his position.

      Unfortunately, Baker’s back pain did not subside, so he consulted

another plant physician on July 30, as well as Dr. Troll again on

September 2. Both doctors recommended Baker treat his pain with over-

the-counter analgesics, ice, and light physical therapy.          Baker’s pain

gradually increased, but he was able to continue performing his assigned

job duties despite the discomfort.        However, because he continued to

experience pain, he consulted Dr. Troll four more times in December. At

his December 2 appointment—just over six months following the

accident—Dr. Troll ordered x-rays and an MRI of Baker’s lumbosacral

spine and prescribed Tramadol to address Baker’s persistent pain. The

MRI study revealed Baker had mild lumbar degenerative changes

consistent with normal wear and tear. Although Baker reported ongoing

low back pain, Dr. Troll’s progress note for a December 16 exam reveals

Baker was instructed to work at regular duty. Dr. Troll did not assign

any lifting or other specific restrictions on Baker’s exertion.
                                     4

       In January 2011, Dr. Troll referred Baker to Dr. Hansen, a pain

management specialist. Dr. Hansen administered injections for Baker’s

pain   and   prescribed   other   medications,    including   Hydrocodone,

Tizanidine, and Tramadol.     Baker testified that by the time he began

seeing Dr. Hansen, he had realized his back injury would affect his job

performance and his life in general.      On April 1, Baker underwent a

radiofrequency denervation procedure, causing him to miss work for the

first time since the incident on May 23, 2010. Bridgestone paid for this

medical treatment provided by Dr. Hansen but did not pay Baker wages

or compensation benefits for the five days of missed work. In July 2011,

Dr. Troll again advised Baker to “work at his own pace.” Dr. Hansen

provided treatment for Baker through May 2012.

       On May 23, 2012, Bridgestone notified Baker that it would no

longer pay for his medical care, as it believed the two-year statute of

limitations for workers’ compensation benefits had expired. At that time,

Baker sought treatment from his family doctor, Dr. Davis, to continue his

pain management.       Baker paid for this and subsequent medical

treatment through his own health insurance plan.

       On June 20, 2012, Baker filed two petitions with the Iowa Workers’

Compensation Commission seeking benefits for his back injury.         One

petition alleged an injury date of May 23, 2010; the other petition alleged

a cumulative injury arising on June 19, 2012.            The commission

consolidated the petitions for hearing.

       After a hearing, a deputy commissioner issued an arbitration

decision ruling that Baker did not sustain a cumulative injury on

June 19, 2012, and that the two-year statute of limitations in Iowa Code

section 85.26 (2009) barred Baker’s claim.       The deputy commissioner

found Baker knew or should have known his condition was serious
                                           5

before June 20, 2010 because (1) he reported the injury; (2) he sought

medical treatment by visiting Dr. Troll on May 25; (3) Dr. Troll imposed

“work restrictions” by instructing Baker to work at his own pace;

(4) Baker underwent some physical therapy; and (5) Baker testified his

symptoms never went away after May 23, 2010.                   However, the deputy

also found “no quarrel” with Baker’s testimony that he did not anticipate

permanent adverse impact on his employment until after June 20, 2010.

Ultimately, the deputy concluded these facts actually did not matter

because the discovery rule only applied to cumulative injuries and Baker

did not prove a cumulative injury.

       Baker filed an intra-agency appeal.             The commissioner’s appeal

decision also determined Baker’s claim was time-barred and concluded

the discovery rule is categorically inapplicable to workers’ compensation

claims arising out of a singular event.               The commissioner’s appeal

decision “affirm[ed] and adopt[ed]” the deputy’s arbitration decision

except for new analysis “on the issue of the discovery rule in traumatic

injury claims.” The commissioner’s appeal decision acknowledged that

“traumatic injuries commonly fail to be instantly disabling or otherwise

have an immediate significant impact on employment,” but nonetheless

affirmed the deputy’s reliance on Clark v. City of Spencer, Iowa Workers’

Comp. Comm’n No. 5017329, 2007 WL 2707714, as agency precedent

precluding application of the discovery rule in this case.

       Baker filed a petition for judicial review in the district court. 2 The

district   court   reversed     the   commissioner’s       ruling,    concluded the

discovery rule can apply to injury claims arising from singular events,


       2Baker’s petition for judicial review did not challenge the agency’s determination

that the injury in this case was not a cumulative injury.
                                    6

and remanded to the agency for a determination whether the discovery

rule extended Baker’s time to file to at least June 20, 2012. Bridgestone

appealed, and we retained the appeal.

      II. Scope of Review.

      The issue we must resolve is whether the discovery rule can be

applied in determining when the period of limitation commences for

workers’ compensation claims arising out of a singular event.       “Iowa

Code chapter 17A governs judicial review of the decisions of the workers’

compensation commissioner.”      Mycogen Seeds v. Sands, 686 N.W.2d

457, 463 (Iowa 2004). Under Iowa Code section 17A.19 “we are free to

substitute our own interpretation of statutes ‘whose interpretation[s]

ha[ve] not clearly been vested’ in the agency.” Roberts Dairy v. Billick,

861 N.W.2d 814, 817 (Iowa 2015) (quoting Iowa Code § 17A.19(10)(c)).

      The legislature has not expressly granted the commissioner

authority to interpret section 85.26, which prescribes periods of

limitation for workers’ compensation cases.     See Iowa Code § 85.26.

Normally, in the absence of an express grant of interpretive authority, we

must determine whether the legislature has nonetheless “clearly vested

the agency with authority to interpret the statutes at issue.” Xenia Rural

Water Dist. v. Vegors, 786 N.W.2d 250, 253 (Iowa 2010).          But the

discovery rule question here does not really involve the agency’s

interpretation of the statute; instead, the question is whether the agency

correctly applied the “judicial interpretation that the date of injury

referred to in the statute is the time when the employee discovers the

injury and its probable compensable nature.” Bergen v. Iowa Veterans

Home, 577 N.W.2d 629, 630 (Iowa 1998).       Therefore, our review is for

errors at law.   See Vachon v. State, 514 N.W.2d 442, 443 (Iowa 1994)
                                      7

(applying the errors-at-law standard in determining whether the district

court correctly applied the discovery rule in a tort action).

      III. Analysis.

      As we have already noted, the agency’s ruling in this case relied on

its own prior decision in Clark in concluding the discovery rule does not

apply in workers’ compensation cases arising from singular traumatic

events. Of course, the agency’s interpretation of law does not bind the

court. Finch v. Schneider Specialized Carriers, Inc., 700 N.W.2d 328, 332

(Iowa 2005) (per curiam).     For reasons explained below, the agency’s

decision in Clark is factually and legally inapposite here.

      Section 85.26(1) contains two limitation periods for workers’

compensation cases.        A two-year period applies unless “weekly

compensation benefits are paid under section 86.13.”            Iowa Code

§ 85.26(1). If—as in Clark—the employer has paid weekly compensation

benefits on a claim, the claimant must file “within three years from the

date of the last payment of weekly compensation benefits.” Id. In such

cases, the limitation period is not measured from the occurrence of the

injury. Bergen, 577 N.W.2d at 630. Because no compensation benefits

were paid to Baker, the commissioner erred in concluding the Clark

case—which involved a different limitations period measured from a

different starting point—controlled the agency’s decision in this case. We

now turn to the question whether the commissioner also erred in

concluding the discovery rule does not apply in workers’ compensation

cases arising from a singular incident.

      A.   Purpose and Character of Workers’ Compensation.           Iowa

first enacted a workers’ compensation system in 1913. 1913 Iowa Acts

ch. 147; Hansen v. State, 249 Iowa 1147, 1150, 91 N.W.2d 555, 556

(1958) (recognizing the 1913 enactment was “[t]he original work[ers’]
                                          8

compensation act” in Iowa). “By 1920 all but eight states had adopted

compensation acts,” and by the mid-1960s, all fifty had.             1 Arthur

Larson et al., Larson’s Workers’ Compensation Law § 2.08, at 2-15 (rev.

ed. 2015) [hereinafter Larson].          “The purpose, intent, and scheme of

work[ers’] compensation legislation is well understood . . . .” Flint v. City

of Eldon, 191 Iowa 845, 847, 183 N.W. 344, 345 (1921). A fundamental

principle undergirding workers’ compensation law is the proposition

       that the disability of a work[er] resulting from an injury
       arising out of and in the course of his [or her] employment is
       a loss that should be borne by the industry itself . . . and not
       suffered alone by the work[er] or the employer, depending on
       individual fault or negligence.

Tunnicliff v. Bettendorf, 204 Iowa 168, 171, 214 N.W. 516, 517–18 (1927).

To accomplish their purpose, workers’ compensation systems impose a

series of tradeoffs. See Ganske v. Spahn & Rose Lumber Co., 580 N.W.2d

812, 814 (Iowa 1998) (discussing “the quid pro quo rationale underlying”

workers’ compensation); see also Henry v. State Comp. Ins. Fund, 982

P.2d 456, 458 (Mont. 1999) (noting workers’ compensation systems are

“premised on a compromise”).

       In the grand bargain removing workers’ compensation matters

from   the   civil   justice   system,    employers   receive   immunity   from

potentially large tort lawsuits and jury verdicts on the condition that they

pay compensation benefits for injuries arising out of and in the course of

employment without regard to fault. See 1913 Iowa Acts ch. 147, § 1(a)

(relieving employers “from other liability for recovery of damages or other

compensation for . . . personal injury”); see also McGarrah v. State

Accident Ins. Fund Corp., 675 P.2d 159, 168 (Or. 1983) (“[E]mployers,

regardless of fault, [must] compensate employe[e]s for injuries arising out

of and in the course of employment.”).
                                    9

      The workers’ compensation bargain also requires claimants to

relinquish rights they would otherwise maintain against their employers.

Claimants cede the prospect of pressing tort lawsuits in exchange for a

system designed to provide compensation benefits and medical services

promptly, without protracted and expensive litigation.      See Flint, 191

Iowa at 847, 183 N.W. at 345; see also Grinnell Coll. v. Osborn, 751

N.W.2d 396, 400 (Iowa 2008) (“The process sought to establish an

administrative tribunal that would provide for the prompt and efficient

determination and award of compensation to injured workers.”); Morrison

v. Century Eng’g, 434 N.W.2d 874, 877 (Iowa 1989) (“The system is

designed to be essentially nonadversarial. . . . [It] presupposes that all

workers will benefit more if claims are processed routinely and paid

quickly.”); Conrad v. Midwest Coal Co., 231 Iowa 53, 64, 300 N.W. 721,

727 (1941) (noting the workers’ compensation system “was adopted by

our legislature as a means of avoiding lengthy litigation that might grow

out of industrial accidents”).

      Larson explains the essence and mutual benefit of these tradeoffs:

      [N]egligence and fault are largely immaterial, both in the
      sense that the employee’s contributory negligence does not
      lessen his or her rights and in the sense that the employer’s
      complete freedom from fault does not lessen its liability
      . . . [.] [T]he employee and his or her dependents, in
      exchange for [some] modest but assured benefits, give up
      their common-law right to sue the employer for damages for
      any injury covered by the act[.]

1 Larson § 1.01, at 1-2 to -3; accord Harned v. Farmland Foods, Inc., 331

N.W.2d 98, 100 (Iowa 1983) (“The legislature has plainly tried . . . to

protect employers from facing tort suits brought by injured employees. It

should certainly not be necessary to repeat here that this protection is in

exchange for advantages to employees . . . .”); Mitchell v. Phillips Mining

Co., 181 Iowa 600, 607, 165 N.W. 108, 110 (1917) (acknowledging the
                                    10

purpose of workers’ compensation was to allow employers to “escape the

evils of personal injury litigation” yet provide employees with “reasonable

compensation for injuries received in their employment”); Henry, 982

P.2d at 458 (“[W]orkers g[i]ve up their right to sue employers in tort for

work-related injuries in exchange for a guaranteed compensation

system.”); Meadows v. Lewis, 307 S.E.2d 625, 638 (W. Va. 1983) (“The

benefits of this system accrue both to the employer, who is relieved from

common-law tort liability . . . , and to the employee, who is assured

prompt payment of benefits.”). “[U]nlike tort, the right to benefits and

[the] amount of benefits are based largely on a social theory of providing

support and preventing destitution, rather than settling accounts

between two individuals according to their personal deserts or blame.” 1

Larson § 1.02, at 1-3.

       The workers’ compensation system establishes a relationship

between injured employees and their employers that is notably different

from the relationship between plaintiffs and defendants litigating at

arm’s length in personal injury cases. See Morrison, 434 N.W.2d at 877

(noting   the   workers’   compensation    system    is   intended   to   be

nonadversarial); cf. Meadows, 307 S.E.2d at 638 (“[C]haracterization of

workers’ compensation proceedings as ‘adversarial’ is not consistent with

the purpose of the . . . Act.”). One stark illustration of the difference is

employers’ obligation to promptly furnish reasonable medical services for

the care of their employees’ work-related injuries. Iowa Code § 85.27(1),

(4).   Employers promptly furnishing such medical services for their

injured workers are entitled to choose the physician who will perform the

services. Id. § 85.27(4). In promptly furnishing reasonable medical care

to injured employees under chapter 85, employers are empowered to

substitute their judgment for that of their injured employees on the
                                          11

important question of which medical professionals are best suited to

diagnose and treat work-related injuries. 3 Tortfeasors have no corollary

control over the selection of their victims’ medical providers.

         The unique relationship between employers and their injured

workers in our workers’ compensation system is further evidenced by the

employer’s obligation to pay compensation benefits in the correct amount

promptly when they are owed to injured employees.                         A statutory

provision promotes voluntary compliance with this obligation by

authorizing an award of additional benefits “up to fifty percent of the

amount of benefits that were denied, delayed, or terminated without

reasonable or probable cause or excuse.”                    Id. § 86.13(4)(a).        In

furtherance of prompt payment of compensation benefits, the statute

requires employers to reasonably investigate claims. Id. § 86.13(4)(c)(1).

These      statutory    provisions     justify    injured     employees’      corollary

expectation that compensation benefits for temporary or permanent

disability will be paid to them when they are owed without litigation and

delay.

         The unique relationship between employers and their injured

employees under the grand bargain of workers’ compensation also

animates a rule of statutory interpretation deeply embedded throughout

our caselaw.      We liberally construe workers’ compensation statutes in




         3Of course, employers’ authority to choose the medical providers who will
diagnose and treat injured workers is not boundless. If an employee believes the
medical care provided by the employer is not offered promptly or is not reasonably
suited to treat an injury, the employee may file a petition for alternate care. Iowa Code
§ 85.27(4).
                                         12

claimants’ favor to effectuate the statute’s humanitarian and beneficent

purpose. 4

       The ultimate takeaway is this: “[T]ort litigation is an adversary

contest to right a wrong between the contestants; workers’ compensation

is a system, not a contest, to supply security to injured workers . . . .” 1

Larson § 1.03[7], at 1-13. This characterization is just as true today as it

was when Iowa first established its workers’ compensation system. See

P.D.S.I. v. Peterson, 685 N.W.2d 627, 635 (Iowa 2004) (concluding a fault-

based interpretation of statutes “has no place in workers’ compensation

law”); cf. Marovec v. PMX Indus., 693 N.W.2d 779, 787 (Iowa 2005)

(concluding language from Flint describing the purpose of workers’

compensation is just as true now as it was then).                        With this

understanding of the obligations and expectations of the parties in

workers’ compensation cases, we now turn to section 85.26, our caselaw,

and the particular circumstances of this case.

       B. Iowa Law Through 1980. “Prior to the . . . Fortieth General

Assembly (extra session), there was no statute of limitations applicable to

claims arising under the Work[ers’] Compensation Law.”                  Hinrichs v.

Davenport Locomotive Works, 203 Iowa 1395, 1398, 214 N.W. 585, 586

(1927); see H.F. 42, § 23-a1, 40th Ex. G.A. (Iowa 1924). But beginning

with the 1924 Iowa Code, the statute required workers’ compensation



       4The  cases in which we have acknowledged this principle are numerous and we
will therefore not provide an exhaustive list. However, we have applied it repeatedly,
beginning shortly after the legislature enacted Iowa’s first workers’ compensation
system. See, e.g., Denison Mun. Utils. v. Iowa Workers’ Comp. Comm’r, 857 N.W.2d 230,
234–35 (Iowa 2014); Dillinger v. City of Sioux City, 368 N.W.2d 176, 180 (Iowa 1985);
Usgaard v. Silver Crest Golf Club, 256 Iowa 453, 459, 127 N.W.2d 636, 639 (1964);
Heiliger v. City of Sheldon, 236 Iowa 146, 152, 18 N.W.2d 182, 186 (1945); Walker v.
Speeder Mach. Corp., 213 Iowa 1134, 1143, 240 N.W. 725, 729 (1932); Bidwell Coal Co.
v. Davidson, 187 Iowa 809, 818, 174 N.W. 592, 595 (1919).
                                      13

claimants to commence proceedings within “two years from the date of

the injury causing . . . death or disability.” Iowa Code § 1386 (1924).

      Our first major case examining the interplay between the workers’

compensation statute of limitations and a singular traumatic event was

Otis v. Parrott, 233 Iowa 1039, 8 N.W.2d 708 (1943). In January 1939, a

truck driver sustained several injuries in a highway accident.              Id. at

1040, 8 N.W.2d at 710. Two months later, he developed tuberculosis.

Id. at 1041, 8 N.W.2d at 710. After tuberculosis took the truck driver’s

life, his surviving spouse filed a workers’ compensation action in

February 1941, more than two years after the highway accident but less

than two years after the tuberculosis became apparent. See id.

      We held the action was not timely. See id. Our decision in Otis

focused on the language in the statute at the time requiring proceedings

to begin within two years of “the injury causing . . . death or disability for

which compensation is claimed”:

      [T]he legislature has designated the injury it means. It does
      not mean the compensable injury or the state of facts or
      conditions which first entitle the claimant to compensation.
      It is the causal injury without reference to whether it is
      compensable or not. With this description of the word
      “injury,” we cannot arrive at a conclusion that the “resultant
      injury” was meant by the legislature. In all compensation
      cases there may be two injuries. The first injury, without
      which there can be no compensation case, is synonymous
      with accident. This may be serious or it may be trivial. It
      may result in immediate disability or death, or it may not
      result in disability or death for a long time. If this first injury
      or accident is trivial, then there may be a second injury
      which occurs when the disability arises.             This is the
      resultant injury. It is caused by the first injury. If the
      legislature, by using the single word “injury”, allows the
      courts to speculate on which injury was intended, the courts
      can upon reason and authority arrive at a conclusion that
      the second or resultant injury was meant. When, however,
      the legislature specifies that the causal injury will control,
      then the court is bound by the words of the statute.
                                    14

Id. at 1042–43, 8 N.W.2d at 711; see Iowa Code § 1386 (1939).          We

concluded the statute measured the limitations period from the date of

the singular event, “without reference to the exigencies which arise from

a trivial injury that later causes a compensable injury.” Otis, 233 Iowa at

1043, 8 N.W.2d at 711.

      In 1969, we considered another case in which the claimant based

his claim for benefits on a singular traumatic event.           Mousel v.

Bituminous Material & Supply Co., 169 N.W.2d 763, 764–65 (1969).

While blacktopping roads in 1958, Mousel “received thermal burns about

his face, neck, wrists and arms” when heated oil splattered him. Id. at

764. “He told his foreman about the burns but kept on working and saw

no physician, nor was he asked to . . . .” Id. Almost eight years after his

employment ended, Mousel saw a dermatologist who found the burns

had caused lesions, and the lesions had ulcerated and become

cancerous.    Id.   A deputy commissioner awarded benefits, but the

commissioner’s appeal decision “dismissed the claim as not timely filed,”

and the district court affirmed.    Id.   Applying the Otis rule, we also

concluded Mousel’s claim for workers’ compensation benefits was

untimely. Id. at 767.

      A few years after Mousel was decided, however, the legislature

enacted new language in the statute of limitations for workers’

compensation claims. See 1977 Iowa Acts ch. 51, § 2 (codified at Iowa

Code § 85.26 (1979)) (providing claims for workers’ compensation

benefits must be “commenced within two years from the date of the

occurrence of the injury for which benefits are claimed,” or if weekly
                                          15

compensation benefits were paid under section 86.13, “within three

years from the date of the last payment of weekly benefits”). 5

       In 1980, we considered the amendment for the first time and

concluded the discovery rule is generally available under section 85.26.

Orr v. Lewis Cent. Sch. Dist., 298 N.W.2d 256, 261 (Iowa 1980). In Orr,

the claimant “was struck on the back of the neck by a falling plank” in

May 1975.         Id. at 257.        However, he did not file for workers’

compensation benefits until 1978.            Id.   Orr contended his action was

timely because he was seeking benefits for headaches and, “despite

reasonable diligence, he was unable to determine the headaches were

caused by the May 1975 incident until September 1977.” Id.

       We acknowledged the Otis rule in Orr. See id. at 258 (noting that

under Otis, the section 85.26 “limitations period started on the date of

the accident”).      We also noted that we had “not been required to

reexamine the holding in Otis since the decision in Mousel.” Id. at 259.

We reasoned that significant developments since Otis—“uncertainty in

the law after . . . Mousel, the general trend toward adoption of the

discovery rule under similar statutes, and the context in which the

[1977] amendment occurred”—led strongly toward making the discovery

rule available under section 85.26. Id. at 260. Ultimately, “[b]ecause the

[1977] amendment removed the language which had been determinative

in Otis,” we concluded “the legislature intended to remove the

uncertainty following Mousel concerning whether the discovery rule was

applicable under section 85.26.”           Id. at 260–61.      This conclusion was


       5The  fact that section 85.26 does not refer to the discovery rule is not unusual.
See 11 Larson § 126.05[2], at 126-19 (“The usual [workers’ compensation] statute
merely dates the period from the time of injury . . . , saying nothing about time of
discovery of the nature of the condition.”).
                                     16

consistent with the proposition that “[c]ourts do not favor statutes of

limitations.     When two interpretations of a limitations statute are

possible, the one giving the longer period to a litigant seeking relief is to

be preferred and applied.” Id. at 261. Accordingly, we overruled Otis.

Id.

      C.       Application of the Discovery Rule Since 1980.             Orr

established that for discovery rule purposes, the statute of limitations on

a workers’ compensation claim does not begin to run until the claimant

knows or should recognize the nature, seriousness, and probable

compensable character of his or her injury.       See id. at 257.   We have

applied this rule in several cases involving cumulative injuries or

occupational diseases that developed over time. See, e.g., Herrera v. IBP,

Inc., 633 N.W.2d 284, 288 (Iowa 2001); Ranney v. Parawax Co., 582

N.W.2d 152, 154–55 (Iowa 1998); McKeever Custom Cabinets v. Smith,

379 N.W.2d 368, 373 (Iowa 1985).          A cumulative injury is deemed to

have occurred when it manifests—and “manifestation” is that point in

time when “both the fact of the injury and the causal relationship of the

injury to the claimant’s employment would have become plainly apparent

to a reasonable person.” Oscar Mayer Foods Corp. v. Tasler, 483 N.W.2d

824, 829 (Iowa 1992) (quoting Peoria Cty. Belwood Nursing Home v.

Indus. Comm’n, 505 N.E.2d 1026, 1029 (Ill. 1987)). In such cases, “[t]he

preferred analysis is to first determine the date the injury is deemed to

have occurred . . . , and then to examine whether the statutory

[limitations] period commenced on that date or whether it commenced

upon a later date based upon application of the discovery rule.” Herrera,

633 N.W.2d at 288.

      This case, however, does not involve a cumulative injury or

occupational disease.    Rather, Baker suffered some pain immediately
                                     17

from an identifiable singular event on May 23, 2010, but claims he was

not aware of the nature, seriousness, or probable compensable character

of his injury until at least June 20, 2010. Bridgestone contends, and the

commissioner concluded, that the limitations period for Baker’s claim

expired on May 23, 2012, because the discovery rule has no application

in such a case. We disagree with Bridgestone and the commissioner.

      We have applied the discovery rule in several singular event cases

since Orr. For example, in Dillinger v. City of Sioux City, the claimant fell

into a pit and injured his back in October 1975 when a ladder gave way.

368 N.W.2d 176, 179 (Iowa 1985).          He notified his employer of the

incident but continued to work and did not immediately seek medical

treatment. See id. at 178–79. Dillinger kept working for a year and a

half “until the pain forced him to terminate his employment.” Id. at 179.

He filed for workers’ compensation benefits in April 1978, about two

years and six months after the work-related traumatic incident. See id.

He contended he had timely filed the claim because he did not know his

back injury was serious until he had surgery to remove a herniated disc

in December 1977 and his physician opined the 1975 fall was a causal

factor. See id. at 178–79. We concluded substantial evidence supported

the agency’s conclusion—which was unquestionably based on the

discovery rule—that the action was timely.         Id. at 182.     Although

Dillinger knew he injured his back when he fell, he continued to work

despite his pain for several months after the traumatic incident.

Substantial evidence supported the commissioner’s finding that Dillinger

did not know until later about the seriousness of his injury or its

potentially permanent effect on his ability to work. See id.

      In Herrera, we further explicated the meaning of the “seriousness”

component of the discovery rule in the workers’ compensation context.
                                    18

We concluded the limitations period does not commence “until the

employee . . . knows that the physical condition is serious enough to

have a permanent adverse impact on the claimant’s employment or

employability.” Herrera, 633 N.W.2d at 288. We have since repeated this

formulation. Larson Mfg. Co. v. Thorson, 763 N.W.2d 842, 854–55 (Iowa

2009); Midwest Ambulance Serv. v. Ruud, 754 N.W.2d 860, 865 (Iowa

2008).     In Larson, we reaffirmed that the phrase “permanent adverse

impact” provides an abbreviated or alternative characterization of the

three elements of the discovery rule test: nature, seriousness, and

probable compensable character of the injury.       See Larson Mfg., 763

N.W.2d at 855. (connecting “permanent adverse impact” with the three-

element test using the abbreviation “i.e.,” meaning “in other words”).

         Bridgestone contends our decision in Swartzendruber v. Schimmel,

613 N.W.2d 646 (Iowa 2000), stands for the proposition that the

discovery rule has no application in claims based upon a singular

traumatic incident. In Swartzendruber, the claimant worked a full day

stocking shelves at a grocery store but experienced pain in his hip and

back by the time the work shift ended. Id. at 648. He awoke the next

morning and could barely walk, with even more intense pain in his back

and hip. Id. He promptly went to a hospital emergency room. Id. X-

rays taken at that time revealed Swartzendruber’s prosthetic hip was

loose.     Id.   After seeing an orthopedic physician who recommended

surgery, he never worked at the grocery store again.       Id.   He filed a

workers’ compensation proceeding two years and four days after the

onset of hip pain—and two years and three days after x-rays revealed the

hip joint defect—but less than two years after consulting the orthopedist

who recommended surgery. See id. at 649.
                                             19

      Our        decision     in     Swartzendruber     discussed       the   analytical

framework for cases presenting pure latent injuries and distinguished it

from the framework controlling personal injury cases in which traumatic

events cause latent manifestation of injuries. Id. at 650; see LeBeau v.

Dimig, 446 N.W.2d 800, 802 (Iowa 1989). We then stated that under the

latter framework, “the statute of limitations begins to run from the initial

injury, not when the injury is later discovered.                 The discovery rule is

actually applied . . . only to the first injury in ‘traumatic event/latent

manifestation’ cases.”             Swartzendruber, 613 N.W.2d at 650 (citation

omitted).

      Bridgestone contends Swartzendruber stands for the proposition

that the discovery rule does not apply if the claimant’s injury arises from

a single traumatic event. This contention flows from a misunderstanding

of Swartzendruber, however, because we applied the discovery rule

analysis    in     that     case     and    concluded    the     rule   did   not   save

Swartzendruber’s claim. Id. at 650–51. Our analysis in Swartzendruber

focused specifically on the seriousness component of the rule:

            The seriousness component of the discovery rule exists
      so that “every minor ache, pain, or symptom” does not begin
      the statute of limitations. Thus, the failure to file a claim
      within two years of the occurrence of the injury may be
      excused if the claimant had no reason to believe the
      condition was serious. If the injury is trivial or minor, or the
      symptoms indicate no serious trouble, the seriousness
      component is not met.

Id. at 650 (citations omitted) (quoting 2B Arthur Larson, Workers’

Compensation        §     78.41(e),    at   15-279    (1994)).      We    refrained   in

Swartzendruber “from pinpointing any specific event to establish the

seriousness of an injury, such as going to a physician or missing work.”

Id. at 651. We further noted a “reasonable worker would not necessarily
                                      20

be charged with knowledge of a compensable injury after experiencing

back or hip pain following work which required bending.” Id.

      Just as not every ache, pain, or symptom is immediately known to

be compensable, not every ache, pain, or symptom will satisfy the

seriousness component of the discovery rule. See id. at 650. Consistent

with our more recent decision in Herrera, not every ache, pain, or

symptom will be understood as possibly suggesting a permanent adverse

impact on a claimant’s health or physical capacity for employment.

Herrera, 633 N.W.2d at 288.

      Our   conclusion   that   the     discovery   rule   could   not   save

Swartzendruber’s claim was based on the uncontroverted fact that an

emergency room physician diagnosed Swartzendruber’s loose prosthetic

hip the morning after the onset of severe hip and back pain and referred

him to an orthopedic specialist.      Swartzendruber, 613 N.W.2d at 651.

Because Swartzendruber did not file his claim within two years of the

medical diagnosis of the serious hip joint defect and referral to the

specialist, we concluded his claim was time-barred as a matter of law.

Id.

      However, the determination “of the question of what constitutes

recognition of the seriousness of an injury or disease is a fact specific

inquiry.”   Id.   The facts in the case now before the court are

distinguishable from those in Swartzendruber.        Baker’s condition was

viewed as a minor muscle strain when Dr. Troll, the plant doctor,

examined him on May 25 and at the time of follow-up appointments in

July and September. Dr. Troll initially prescribed only over-the-counter

medications for pain and advised Baker to perform stretching exercises

during the several weeks after the incident. Additionally, Baker missed

no work and continued to perform his regular job duties at his own pace
                                     21

without specific lifting limitations for several months after the May 23

incident.     Unlike the claimant in Swartzendruber, Baker was not

immediately referred to a specialist.      The record reveals instead that

Dr. Troll ordered no prescription medication, x-rays, or diagnostic scans

for Baker until December 2010.         Although none of these facts are

dispositive on the issue of seriousness, when taken together with the

other evidence in this record they clearly distinguish this case from

Swartzendruber and preclude a summary resolution of the limitations

issue.

         D. Synthesis. Whether a work-related injury arises cumulatively

because of repetitive trauma or from a singular traumatic event, the

agency must apply the discovery rule when it is properly raised and

substantial evidence supports it. In cumulative injury cases, the agency

applies the rule by deciding “whether the statutory period commenced on

[the manifestation] date or whether it commenced upon a later date.”

Herrera, 633 N.W.2d at 288.      In cases alleging injuries arising from a

singular event, the agency must apply the rule in deciding whether the

limitation period commenced on the date of the singular event or at some

later time. If the claimant did not know—or did not have knowledge of

facts sufficient to trigger a duty to investigate—“the nature, seriousness[,]

and probable compensable character” of their injury, Orr, 298 N.W.2d at

261, the discovery rule tolls the limitation period until the claimant gains

that knowledge.      The fact an initial accident is traumatic does not

necessarily provide immediate notice of seriousness or compensability.

See Ga. Pac. Corp. v. Taplin, 586 So. 2d 823, 827 (Miss. 1991).

         As we have explained, claimants and employers have a unique

cooperative relationship in the workers’ compensation context that has

no counterpart in the tort arena.         The discovery rule promotes that
                                        22

relationship   because    it   decreases     the   likelihood    that   workers’

compensation proceedings will be filed before the nature, seriousness,

and probable compensability of claims are known—especially during

periods when employers are interacting cooperatively with claimants and

providing them with appropriate medical services in the aftermath of a

work-related injury that is not perceived as serious.           Cf. Vossoughi v.

Polaschek, 859 N.W.2d 643, 650 (Iowa 2015) (concluding a person with a

possible legal malpractice claim should not have to initiate suit and

sabotage an ongoing cooperative attorney–client relationship when the

person’s injury is only speculative).

      Courts in several other jurisdictions have applied the discovery

rule under circumstances analogous to those presented here, often

noting an onset of back pain does not necessarily indicate a serious

injury. See, e.g., Freeman v. Tiffany Stand & Furniture, 726 S.W.2d 294,

295–96 (Ark. Ct. App. 1987) (concluding a claimant did not know the

extent of his lumbar injury for statute-of-limitations purposes when the

pain was manageable with aspirin and he kept working); Sevin v.

Schwegmann Giant Supermarkets, Inc., 652 So. 2d 1323, 1324, 1327 (La.

1995) (concluding a claim was timely when the initial treatment involved

only rest, physical therapy, and medication, but the claimant continued

experiencing pain and later returned to the doctor); Loud v. Dixie Metal

Co., 475 So. 2d 122, 124–25 (La. Ct. App. 1985) (rejecting an employer’s

contention that “since [the claimant] suffered immediate pain, he was

aware of his compensation claim sufficiently” to commence the

limitations period); Williams v. Dobberstein, 157 N.W.2d 776, 778 (Neb.

1968) (rejecting “the defendants’ position that since the [claimant] knew

that he had an accident, and had pain which he associated with the

accident[,] . . . the statute of limitations began to run on the date of the
                                          23

accident”); Montgomery v. Milldale Farm & Live Stock Improvement Co.,

246 N.W. 734, 735 (Neb. 1933) (concluding a claim was not time-barred

when the claimant initially “relied . . . upon the advice of his physicians

that his injuries were muscular and temporary” rather than serious and

permanent); White v. N.D. Workers Comp. Bureau, 441 N.W.2d 908, 911

(N.D. 1989) (“[W]e disagree with the Bureau’s argument that White’s

claim is barred because he knew the origin of his back pain was the fall

and because he sought medical attention for his back.”); Burcham v.

Carbide & Carbon Chems. Corp., 221 S.W.2d 888, 892 (Tenn. 1949)

(ascribing significance to the company doctor’s initial and minimal

diagnosis); Teague v. Tex. Emp’rs’ Ins. Ass’n, 368 S.W.2d 643, 644–45

(Tex. Civ. App. 1963) (“We . . . cannot find that [claim]ant had any

symptoms other than constant pain to warn him that he might have

been injured in a manner other than the trivial injury first reported to

him by the doctor . . . .”).

       The commissioner erred in concluding the discovery rule has no

application in this case.       Under the circumstances presented here, we

conclude the district court correctly ordered a remand for the agency’s

application of the discovery rule. 6 We therefore affirm the district court’s

decision.    On remand before the commissioner, Baker must “meet his

burden . . . to prove a factual basis for application of the rule.” Orr, 298

N.W.2d at 262.


       6Although   the deputy’s arbitration decision included a finding that Baker
understood the seriousness of his injury before June 20, 2010, the deputy also found
no quarrel with Baker’s testimony that he was unaware of the possibility that his injury
would have a permanent impact on his employment until the summer or fall of that
year. Given these findings and the record evidence detailed above, we are unable to
conclude the final agency action provides a basis for reversing the district court’s
decision and affirming the agency’s decision on the alternative ground that application
of the discovery rule would have produced the same result as a matter of law.
                                      24

      IV. Conclusion.

      Whether a work-related injury arises because of a single event or

develops    cumulatively    over   time,   the   discovery   rule   applies   in

determining whether a workers’ compensation claim has been filed

within two years after the occurrence of the injury under section 85.26(1)

(2009). That limitation period does not begin to run until the claimant

knows or in the exercise of reasonable diligence should know “the

nature, seriousness[,] and probable compensable character” of his or her

injury.    Id. at 261.     Because the district court reached the same

conclusion, we affirm its judgment and remand to the district court with

instructions to remand this matter to the commissioner for further

proceedings consistent with this opinion.

      AFFIRMED.
