                 This opinion is subject to revision before final
                      publication in the Pacific Reporter

                                 2015 UT 78


                                    IN THE

       SUPREME COURT OF THE STATE OF UTAH

 WASHINGTON COUNTY SCHOOL DISTRICT and UTAH SCHOOL BOARDS
              RISK MANAGEMENT ASSOCIATION,
                   Petitioners, Appellants,
                                       v.
             LABOR COMMISSION and STEVEN H. BROWN,
                     Respondents, Appellees.

                              No. 20130847
                          Filed August 25, 2015

             On Certiorari to the Utah Court of Appeals

                                 Attorneys:
 Bret A. Gardner, Kristy L. Bertelsen, Salt Lake City, for petitioners
Sherry Hayashi, Jaceson R. Maughan, Salt Lake City for respondents
                        Labor Commission
  Aaron J. Prisbrey, Trevor C. Sanders, St. George, for respondent
                         Steven H. Brown

CHIEF JUSTICE DURRANT authored the opinion of the Court, in which
          ASSOCIATE CHIEF JUSTICE LEE, JUSTICE DURHAM, JUSTICE
              PARRISH, and JUSTICE HIMONAS joined.

   CHIEF JUSTICE DURRANT, opinion of the Court:
                               Introduction
   ¶1 This case concerns the scope of the Utah Workers‘
Compensation Act. Specifically, we are asked to address the causal
connection that an employee must establish between an initial
workplace injury and a subsequent non-workplace injury in order to
recover workers‘ compensation for the subsequent injury. In January


    Justice Parrish sat on this case and voted prior to her resignation
on August 16, 2015.
                  WASHINGTON CNTY. v. LABOR COMM‘N
                          Opinion of the Court
2003, Steven Brown, suffered a back injury when he fell down the
steps of his bus while at work as a school bus driver for the
Washington County School District (School District). This injury
required medical treatment and eventual spinal surgery. He received
workers‘ compensation for this injury. Subsequently, in September
2007, Mr. Brown was reinjured when a child jumped on his back and
knocked him to the ground at a local festival. He required additional
spinal surgery for this second injury.
    ¶2 Mr. Brown requested and received workers‘ compensation
for his second injury. The Administrative Law Judge (ALJ) with the
Utah Labor Commission (Commission) determined that his second
injury was causally linked to his workplace injury and awarded
benefits. The School District appealed the ALJ‘s decision to the
Commission, which affirmed. It then appealed to the court of
appeals, which also affirmed. The School District presents two issues
on appeal.
    ¶3 First, it claims the court of appeals erred in determining that
the second injury was a natural result of the primary injury and thus
compensable under the Utah Workers‘ Compensation Act.
Mr. Brown disagrees. Specifically, the parties argue over what causal
connection is required between the primary workplace injury and
the subsequent non-workplace injury in order to allow workers‘
compensation benefits for the second injury. After reviewing the
statute and our caselaw, we clarify that under the direct and natural
results test we adopted when interpreting the Workers‘
Compensation Act in Mountain State Casing Services v. McKean,1 the
compensable workplace injury must be a significant contributing
cause of the subsequent non-workplace injury. We remand to the
Commission to decide whether Mr. Brown‘s injury meets this
clarified standard.
   ¶4 Second, the School District challenges the court of appeals‘
decision affirming the Commission‘s finding that there were no
conflicting medical reports that required submission of the issue of
medical causation to a medical panel. Because we have clarified the
applicable standard and remand the case to the Commission, we
decline to address the School District‘s second issue. As additional
hearings on medical causation will be required, the ALJ will have to
decide anew if there are conflicting medical opinions and thus
whether a medical panel is appropriate.


   1   706 P.2d 601, 602 (Utah 1985) (per curiam).

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                             Background
    ¶5 This case concerns the causal relationship between injuries
that resulted from two separate incidents involving Mr. Brown.2 The
first incident occurred on January 27, 2003, when Mr. Brown fell
down the steps of a school bus and injured his lower back. At the
time, he was employed as a school bus driver for the Washington
County School District. As a result of the accident, Mr. Brown
received pain management and eventually underwent surgery to
address ―a large extruded disc herniation‖ on the left side of his
lumbar spine. He sought, and was awarded, workers‘ compensation
benefits for this injury and in October 2004, he returned to work
driving a school bus for the School District.
    ¶6 Subsequently, on September 1, 2007, Mr. Brown was
attending the local ―Peach Days‖ celebration when a child jumped
on his back, knocking him to the ground. Following the incident, he
experienced ―constant stabbing, burning pain in his lumbar area that
radiated from his back all the way down his legs.‖ His treating
physicians identified an injury to the right side of his lower back,
and he underwent corrective surgery. Mr. Brown filed for workers‘
compensation benefits, and the School District denied liability,
―assert[ing] that Brown had sustained a subsequent non-industrial
intervening accident . . . over four years after the industrial accident,
for which [it] did not have workers‘ compensation liability.‖ An ALJ
with the Labor Commission held a hearing and concluded that ―all
medical evidence support[ed] a finding that the prior industrial disc
injury was a contributing cause to the outcome and injury resulting
from the festival incident.‖ The School District appealed this decision
to the Commission, which affirmed the ALJ‘s decision. It then
appealed to the court of appeals, which affirmed the Commission‘s
decision.3 Below, we review the medical evidence and then discuss
the parties‘ arguments on appeal.
    ¶7 Following Mr. Brown‘s fall from the bus in January 2003, he
was treated for left-side lower-back pain by Dr. Dale Stott. Dr. Stott
attempted to manage his pain with various procedures, including
steroid injections and a nerve block. But Mr. Brown continued to


   2 The parties did not challenge the facts as recited by the court of
appeals in Washington County School District v. Labor Commission,
2013 UT App 205, ¶¶ 2−15, 45, 309 P.3d 299. Therefore, we recite the
facts consistent with the court of appeals opinion.
   3   Id. ¶ 45.

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                       Opinion of the Court
experience back pain and was referred to a spinal surgeon, Dr. Mark
Kabins. In August 2004, Mr. Brown was given an MRI and
Dr. Kabins concluded based on the MRI that he was suffering from a
large disk herniation and sequestration in his lower spine at L4/5—
the fluid between these disks had ruptured, been squeezed out, and
separated from the main part of the disk. In late August 2004,
Dr. Kabins performed surgery on the left side of Mr. Brown‘s lower
spine to repair this damage. In postoperative examinations,
Dr. Kabins noted that Mr. Brown ―does have intermittent back
discomfort, but is clearly improved and stable.‖ Dr. Kabins
prescribed pain medication and treated Mr. Brown again for a flare-
up of back discomfort in mid-October 2004. But three weeks later,
Dr. Kabins reported that Mr. Brown was ―doing well with minimal
discomfort.‖ Mr. Brown returned to work for the School District as a
bus driver in October 2004.
    ¶8 Mr. Brown did not seek medical attention for his back for
more than two years. But in March 2007, Mr. Brown visited Dr. Stott
and reported low back pain and pain and numbness in his left leg.
He indicated that this pain had existed during the prior two years
and that he suffered daily. Dr. Stott diagnosed Mr. Brown with
―Failed Back Surgery Syndrome‖ and ―[p]robable recurrent disc
herniation,‖ and ordered an MRI. The March 2007 MRI revealed a
reoccurrence of issues at the previous injury site. Specifically, it
showed an L4/5 recurrent disc extrusion, meaning that the disk had
ruptured and fluid had been excreted. The MRI indicated that this
injury was also affecting the right side of Mr. Brown‘s spine. The
radiology report found that the disc extrusion had mildly
compromised both the lateral recesses, the area within the spinal
canal on either side of the spine, and the right neuroforamen, the
opening on the right side of the vertebra that allows nerves to pass
from the spinal cord to other parts of the body. Dr. Stott tried to
manage Mr. Brown‘s pain with steroid injections in April and May
2007.
   ¶9 In addition to the March 2007 flare-up, Mr. Brown ―testified
that he never recovered from the January 27, 2003 accident and was
always stiff and sore and would have flair [sic] ups that required
pain medication.‖ This pain medication was covered by workers‘
compensation.
    ¶10 Four months after receiving steroid injections for his back
pain, Mr. Brown was injured while attending a local festival when a
child jumped onto his back, knocking him to the ground. Mr. Brown
did not see, and could not identify, the child who jumped on him.
Following the incident, he suffered from ―constant stabbing, burning

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                         Opinion of the Court
pain in the lumbar area which radiated to the buttock bilaterally and
down his legs.‖ Mr. Brown visited Dr. Stott on September 19
concerning his back pain. Dr. Stott again diagnosed him with ―Failed
Back Surgery Syndrome‖ and ―[l]umbar radiculopathy.‖ A
subsequent MRI showed ―a large extruded disc herniation at the L4-
5 level, which is the same level of his previous work-related injury,
but on the opposite side of the disc.‖
   ¶11 In October 2007, Mr. Brown consulted with Dr. Kabins—the
doctor who had performed his previous spinal surgery. Based on his
examination of Mr. Brown, Dr. Kabins decided surgery was
appropriate. Mr. Brown then consulted Dr. Gary Snook, who
diagnosed him with ―[i]ntervertebral disc disorder with myelopathy,
lumbar region‖ and performed surgery in November 2007. A follow-
up surgery was performed to remove some remaining disc
fragments that were causing significant pain.
    ¶12 Three doctors expressed medical opinions regarding
whether the January 2003 injury had contributed to the September
2007 injury. All expressed the opinion that there was some causal
connection. Dr. Richard Knoebel examined Mr. Brown at the request
of the School District in March 2008, after Mr. Brown had filed a
claim for workers‘ compensation for the 2007 injury. In his report,
Dr. Knoebel concluded that ―it must be said with a reasonable
degree of medical probability that ‗the initial work-related accident
(is merely) a contributing cause of the subsequent injury.‘‖ He also
stated that, ―[i]n summary, from a medical viewpoint, the significant
incident requiring subsequent surgery by Dr. Snook was the non-
industrial 9/1/07 aggravation of the patient‘s low back and L4/5
disc. There was a small contribution only from the patient’s pre-existing
degenerative L4/5 disc and the prior 1/27/03 industrial incident with
surgery.‖ (Emphasis added). He also stated that the prior workplace
injury ―certainly was not the most important or significant cause‖
but was ―a very minor contributing cause.‖ (Emphasis added). Further,
he stated that ―the prior disc surgery with residual L4/5 disc
extrusion already narrowing the right neural fragment is considered,
with a reasonable degree of medical probability, a contributing cause.‖
(Emphasis added).
   ¶13 After discussions with counsel for the School District,
Dr. Knoebel expressed his opinion that ―the disc herniation in 2007
was not the ‗natural result‘ of the prior industrial event and that the
significant cause for the recurrent disc herniation at L4/5 was the
nonindustrial permanent aggravation of 9/1/07.‖ Both the ALJ and
the court of appeals did not consider Dr. Knoebel‘s last opinion in
their analysis. They concluded that this final opinion, made after

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                WASHINGTON CNTY. v. LABOR COMM‘N
                          Opinion of the Court
discussions with counsel and couched in legal language, opined on
legal causation instead of medical causation.
    ¶14 Dr. Gary Snook—who performed Mr. Brown‘s second spinal
surgery—checked yes when asked ―[i]s there a medical causal
relationship between the industrial exposure and the problems for
which you have been treating the employee‖ on a signed ―Treating
Physician Opinion‖ form that is part of Mr. Brown‘s Medical
Records Exhibit. He did not express an opinion as to the strength of
this causal relationship.
    ¶15 Dr. Kabins—who performed Mr. Brown‘s initial spinal
surgery, examined him after the 2007 incident, and recommended
his second surgery—opined that ―certainly it appears that the causality
for the herniated disc is multifactorial, that being preexisting process in
the industrial injury, as well as an acute process from the recent
attack/incident.‖ But Dr. Kabins did not directly address the
strength of the causal relationship.
    ¶16 An ALJ with the Commission held a hearing to determine if
Mr. Brown would receive workers‘ compensation benefits for the
medical treatment and disability that occurred after the 2007
incident. The ALJ considered the medical evidence detailed above,
including the opinions of Dr. Knoebel, Dr. Snook, and Dr. Kabins,
and issued a written decision finding that ―[a]ll medical evidence
supports a finding that the prior industrial disc injury was a
contributing cause to the outcome and injury resulting from the
festival incident in that petitioner‘s disc at the L4/5 level with its
‗residual‘ disc extrusion and ‗already narrowing‘ right neural
fragment was a contributing cause to the injury.‖ (Emphasis added).
The ALJ also found that ―there was no break in the chain of
causation between his original work accident and his injury after the
September 2007 incident‖ because there was ―no evidence that
Mr. Brown was engaged in any rash or foolhardy conduct.‖ The ALJ
declined to appoint a medical panel to resolve conflicts between the
medical opinions, instead finding there was no conflict. The School
District appealed the decision to the Commission challenging the
ALJ‘s findings of medical causation and her failure to refer the case
to a medical panel. The Commission upheld the ALJ‘s decision on
both issues and awarded Mr. Brown the additional workers‘
compensation benefits. The School District appealed to the court of
appeals, which upheld the agency‘s decision. We granted certiorari
on the appeal and have jurisdiction under Utah Code section 78A-3-
102(3)(a).



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                           Opinion of the Court
                           Standard of Review
    ¶17 The School District now appeals from the court of appeals‘
decision.4 It presents two issues on appeal. First, the School District
argues that the court of appeals erred in holding that the non-
workplace injury could be deemed a natural result of the prior
industrial injury. We review the court of appeals‘ application of a
legal standard for correctness.5 The application of this legal standard
to the facts of the case is a mixed question of fact and law, which we
can review under a deferential or non-deferential standard,
depending on a number of factors.6 But here, because we only
address and clarify the legal standard and decline to apply this
standard to the facts of the case, we need go no further in our
traditional standard of review analysis.7
    ¶18 Second, the School District asks us to decide whether the
court of appeals erred in affirming the Commission‘s determination
that there were no conflicting medical reports that required
submission of the issue of medical causation to a medical panel. This
is an issue of fact reviewed under a substantial evidence standard.8
Under this standard, we ―must uphold the Commission‘s factual




   4 See Washington Cnty. Sch. Dist. v. Labor Comm’n, 2013 UT App
205, 309 P.3d 299.
   5   Murray v. Utah Labor Comm’n, 2013 UT 38, ¶ 7, 308 P.3d 461.
   6Id. ¶ 36. The standard of review for mixed questions can either
be deferential or non-deferential depending on three factors:
         (1) the degree of variety and complexity in the facts to
         which the legal rule is to be applied; (2) the degree to
         which a trial court‘s application of the legal rule relies
         on ‗facts‘ observed by the trial judge, such as witness‘s
         appearance and demeanor, relevant to the application
         of the law that cannot be adequately reflected in the
         record available to the appellate courts; and (3) other
         policy reasons that weigh for or against granting
         [deference] to trial courts.
   Id. (alteration in original) (internal quotation marks omitted).
   7 See Manzanares v. Byington (In re Baby B.), 2012 UT 35, ¶¶ 40−42,
308 P.3d 382.
   8   See UTAH CODE § 63G-4-403(4)(g).

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                 WASHINGTON CNTY. v. LABOR COMM‘N
                         Opinion of the Court
findings if such findings are supported by substantial evidence
based upon the record as a whole.‖9
                                Analysis
    ¶19 Below, we discuss and clarify the causal connection required
between an initial workplace injury and a subsequent non-
workplace injury to allow workers‘ compensation benefits for the
second injury. The court of appeals and the Commission have in
several cases relied upon the direct and natural results test that we
adopted in McKean when interpreting the Act in the subsequent
injury context. But they appear to read this test as requiring only that
the initial workplace injury be a mere contributing cause, or a minor
cause, of the subsequent non-workplace injury. This minimal causal
connection is not supported, however, by the language of the
Workers‘ Compensation Act or a close reading of our prior caselaw.
Accordingly, we clarify that under our direct and natural results test,
the employee must establish that the original workplace injury was a
significant contributing cause of the subsequent non-workplace
injury in order to recover workers‘ compensation benefits.
   ¶20 Because we clarify this causal standard and remand for
additional proceedings, we do not address the issue of whether the
ALJ erred in declining to refer the case to a medical panel. On
remand, the ALJ will be required to conduct a new hearing and
apply the appropriate causal standard. Therefore, the ALJ will need
to reconsider whether the medical evidence presented creates a
conflict under the clarified causal standard.
I. Under the Utah Workers‘ Compensation Act the Initial Workplace
 Injury Must Be a Significant Contributing Cause of the Subsequent
Non-Workplace Injury to Allow Workers‘ Compensation Benefits for
                          the Second Injury
    ¶21 We look first to the Utah Workers‘ Compensation Act and
then to Utah caselaw to determine the appropriate causal standard
to apply in cases such as this. The Workers‘ Compensation Act
provides that an employee who is injured by an accident ―arising out
of and in the course of the employee‘s employment, wherever such
injury occurred, if the accident is not purposely self-inflicted, shall be
paid‖ workers‘ compensation for the loss and medical bills that
result from the injury.10 The Act does not define a personal injury

   9Brown & Root Indus. Serv. v. Indus. Comm’n, 947 P.2d 671, 677
(Utah 1997).
   10   UTAH CODE § 34A-2-401(1).

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                              Opinion of the Court
arising out of and in the course of employment, except to state that it
―includes an injury caused by the willful act of a third person
directed against an employee because of the employee‘s
employment,‖ but ―does not include a disease, except as the disease
results from the [compensable] injury.‖11
    ¶22 In interpreting the Act, we have required a meaningful
causal link between the initial workplace injury and the subsequent
non-workplace injury in order for the employee to recover workers‘
compensation benefits for the second injury. Our early cases
analyzing this issue discussed the necessary causal link between the
two injuries as ―direct‖12 and the initial workplace injury as a
―significant factor‖ in the subsequent non-workplace injury.13
   ¶23 In our 1985 McKean case, we adopted Professor Larson‘s
direct and natural results test when interpreting the Workers‘
Compensation Act in this context.14 Under this test, we analyze both
the causal connection between the two injuries and whether there
was an event that broke the causal chain.15 We do not address the
causal chain issue here as it is not raised in this case. The
Commission found that there was no employee misconduct and thus
the causal chain was not broken. The parties do not challenge this
finding.
   ¶24 We acknowledge that while we have spoken primarily in
terms of ―direct causal connection‖ and ―significant factor‖ in cases
involving subsequent injuries, we have also used language


   11   Id. § 34A-2-102(j).
   12   Makoff Co. v. Indus. Comm’n, 368 P.2d 70, 72 (Utah 1962).
   13 Perchelli v. Utah State Indus. Comm’n, 475 P.2d 835, 837 (Utah
1970).
   14 See Mountain State Casing Servs. v. McKean, 706 P.2d 601, 602
(Utah 1985) (per curiam) (―[A] subsequent injury is compensable if it
is found to be a natural result of a compensable primary injury.‖).
   15 Id. at 603 (noting that an employee can break the chain of
causation between the initial workplace injury and the subsequent
injury in certain instances through negligence or intentional
misconduct); see also 1 LEX K. LARSON, LARSON‘S WORKERS‘
COMPENSATION LAW § 10.05 (2015) (discussing actions by the
employee that may break the causal chain and distinguishing
injuries that arise out of ―quasi-course activity‖ and those that do
not).

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                     WASHINGTON CNTY. v. LABOR COMM‘N
                            Opinion of the Court
indicating that it is enough if the workplace injury is only ―a
contributing cause‖ of the subsequent injury. Specifically, in McKean
we stated that the employee ―is not required to show that his
original tragedy [is] the sole cause of a subsequent injury, but only
that the initial work-related accident was a contributing cause of his
subsequent . . . injury.‖16
    ¶25 Likely as a result of our imprecision in this regard, our court
of appeals has interpreted the direct and natural results test to
require that the employee need show only that the initial workplace
injury was a mere contributing cause of the subsequent non-
workplace injury in order to allow workers‘ compensation benefits.
This application of our direct and natural results test, while
understandable given language in McKean, is not supported by the
language of the Workers‘ Compensation Act or a close reading of
our prior caselaw. Below, we discuss our caselaw on this issue and
the court of appeals interpretation of the test; we then clarify the
appropriate causal standard to apply moving forward and remand
Mr. Brown‘s case to the Commission for further proceedings.
    ¶26 We have interpreted the Utah Workers‘ Compensation Act
in the subsequent injury context in three cases: Makoff Co. v. Industrial
Commission,17 Perchelli v. Utah State Industrial Commission,18 and
Mountain States Casing Services v. McKean.19 First, in Makoff, we held
that the subsequent injury of the employee‘s back was compensable
when he had ongoing back problems following the workplace injury
and the injury flared-up after he bent down to pick up a pair of
pants.20 In that case, we stated that ―[t]he trouser incident was not
independently employment connected, but represented the point at
which the [earlier] industrial accident ripened into a compensable
disability.‖21 We also recognized that under Utah law, ―a subsequent
aggravation or ‗lighting up‘ of a previous injury is compensable if it
is demonstrated that there was a causal relation between the two
[injuries].‖22 Further, we noted that a previous back injury that was

   16   McKean, 706 P.2d at 602 (emphasis added).
   17   368 P.2d 70.
   18   475 P.2d 835.
   19   706 P.2d 601.
   20   Makoff, 368 P.2d at 71−72.
   21   Id. at 72.
   22   Id.

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                           Opinion of the Court
accompanied by severe pain and the need for a back brace could
easily cause a degenerative condition that ―might result in
subsequent surgery and compensable disability in a direct causal
connection‖ with the previous incident.23
    ¶27 Next, in Perchelli, we held that an employee‘s subsequent
back injuries were compensable when these injuries resulted from a
sneezing fit that aggravated his previous workplace back injury.24 In
discussing the causal connection between the two injuries, we stated
that ―there [was] not a scintilla of evidence in the record to support
the conclusion that the sneezing episode [and not the industrial
accident] was the cause of [the] applicant‘s disability.‖25 We also
recognized ―that there was a reasonable medical probability that had
applicant not sneezed, some other episode would have triggered the
actual disc herniation, requiring surgery.‖26 We further noted that
Mr. Perchelli‘s case was clearly distinguishable from a prior case
where ―the [previous workplace] accident was not a significant factor
in causing the condition which required corrective surgery.‖27
    ¶28 Finally, in McKean, we adopted Professor Larson‘s direct
and natural result causal test when interpreting the Workers‘
Compensation Act‘s ―arising out of‖ language in the context of a
subsequent non-workplace injury. We cited Larson‘s treatise on
workers‘ compensation, along with our previous caselaw, for the
proposition that ―[a] subsequent injury is compensable if it is found
to be a natural result of a compensable primary injury.‖28 We also
stated that ―[the employee] is not required to show that his original
tragedy was the sole cause of a subsequent injury, but only that the
initial work-related accident was a contributing cause of his
subsequent . . . injury.‖29
   ¶29 We went on to hold that burns on an employee‘s hand were
the natural result of his initial compensable injury—the severing and
reconnection of his lower arm, which left his hand with loss of


   23   Id. (emphasis added).
   24   475 P.2d at 837.
   25   Id.
   26   Id.
   27   Id. (emphasis added).
   28   McKean, 706 P.2d at 602.
   29   Id.

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                             Opinion of the Court
sensation.30 In his treatise, Larson‘s direct statement of the rule is
that a ―subsequent injury, whether an aggravation of the original
injury or a new and distinct injury, is compensable if it is the direct
and natural result of a compensable primary injury.‖31 Larson also
explains, ―once the work-connected character of any injury, such as a
back injury, has been established, the subsequent progression of that
condition remains compensable so long as the worsening is not
shown to have been produced by an independent nonindustrial
cause.‖32 By discussing the possibility of an independent
nonindustrial cause, Larson contemplates a meaningful causal link
between the initial compensable injury and the subsequent injury in
his direct-and-natural-result test.
    ¶30 A close reading of these three cases provides guidance on
the appropriate causal standard. In them, we discuss a standard that
requires the subsequent injury to be the ―direct‖33 and ―natural
result of a compensable primary injury‖34 in that the primary injury
is a ―significant factor in causing the condition‖ that required further
medical care.35 Further, we have discussed the subsequent injury as a
ripening or aggravation of the primary injury, which suggests a
direct and significant causal link.36
    ¶31 The court of appeals and Commission appear to read our
direct and natural results test to provide compensation for the
subsequent injury if there is any causal connection between the two
injuries—even a very minor connection. Specifically, the court of
appeals appears to have applied this causal standard in this case37


   30   Id. at 603.
   31 1 LEX K. LARSON, LARSON‘S WORKERS‘ COMPENSATION LAW
§ 10.01 (2015).
   32   Id. § 10.02.
   33   Makoff, 368 P.2d at 72.
   34   McKean, 706 P.2d at 602.
   35   Perchelli, 475 P.2d at 837.
   36Id. (noting that ―there may be a direct causal relationship
between an industrial accident and a subsequent disability, although
some other episode may represent the point of time when the
industrial accident ripened into a compensable injury‖).
   37 Washington Cnty. Sch. Dist. v. Labor Comm’n, 2013 UT App 205,
¶ 43, 309 P.3d 299.

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                          Opinion of the Court
and two other decisions that address this issue—McKesson Corp. v.
Labor Commission38 and Oliver v. Labor Commission & Employers’
Reinsurance Fund.39
    ¶32 In McKesson, the court of appeals articulated the rule as
requiring that ―the initial work-related accident [is merely] a
contributing cause of the subsequent injury.‖40 And in a footnote the
court stated that ―the claimant must establish that the subsequent
aggravation is causally linked to the primary compensable injury.‖41
The court cited our decision in McKean where we stated that the
employee ―is not required to show that his original tragedy was the
sole cause of a subsequent injury, but only that the initial work-
related accident was a contributing cause of his subsequent hand
injury.‖42 The court of appeals‘ articulation of the standard, which
added ―merely‖ as a modifier to contributing cause and took out the
comparison to ―sole cause,‖ appears to allow benefits for the
subsequent injury when there is any causal connection with the
initial workplace injury.
    ¶33 While the court of appeals applied this de minimis causal
standard in McKesson, the facts of that case would likely satisfy the
higher causal standard we clarify today. In McKesson, the court of
appeals concluded that an employee‘s aggravation of his original
workplace neck injury was compensable when the medical evidence
showed that the original workplace injury ―never properly healed,
and . . . a subsequent aggravation of that injury was not
unexpected.‖43 The employee in McKesson had injured his neck in
1995 when he was struck in the head by a falling object at work and
subsequently aggravated the injury in 1999 when he hit his head on
his truck door as he pulled himself into the vehicle.44
   ¶34 The next case in which the court of appeals discussed the
causal link required between an initial and subsequent injury is the


   38   2002 UT App 10, 41 P.3d 468.
   39   2013 UT App 301, 318 P.3d 777.
   40McKesson, 2002 UT App 10, ¶ 18 (alteration in original) (internal
quotation marks omitted).
   41   Id. ¶ 18 n.2.
   42   McKean, 706 P.2d at 602 (emphasis added).
   43   McKesson, 2002 UT App 10, ¶ 27.
   44   Id. ¶¶ 2, 7.

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                    WASHINGTON CNTY. v. LABOR COMM‘N
                           Opinion of the Court
one now before us. The court of appeals cited to McKean for the
proposition that ―our supreme court has instructed that the ‗natural
result‘ standard does not require an employee ‗to show that his
original tragedy was the sole cause of a subsequent injury, but only
that the initial work-related accident was a contributing cause of his
subsequent . . . injury.‘‖45 In applying this standard, the court
appears to require the workplace injury to be only a small, or minor,
cause of the subsequent non-workplace injury. The court noted that
         [b]oth the ALJ and the Commission combined the
         medical causation information provided by the
         experts—including Dr. Knoebel‘s opinion that the 2003
         accident was a ‘very minor contributing cause’—with an
         examination of the facts and circumstances to arrive at
         the conclusion that Mr. Brown had proved by a
         preponderance of the evidence that the 2007 injuries
         were the natural result of the prior industrial accident
         and his resultant L4−5 damage.46
    ¶35 The court also states that the medical expert testimony had
established that the prior workplace injury had ―contributed to some
extent‖ to the subsequent injury47 and that all the experts concluded
that the 2003 accident was ―a contributing cause‖ of the injuries he
suffered in 2007.48 Further, the ALJ also articulated a weaker causal
standard in her decision. She states that ―if the claimant can show
that the initial work-related accident is merely a contributing cause of
the subsequent injury,‖ then ―the claimant has met his burden.‖
(Emphasis added).
    ¶36 Finally, in Oliver, a case the court of appeals decided after it
issued its opinion in the case now before us, the court of appeals
articulated the standard as requiring that ―[t]he claimant must first
demonstrate that the subsequent aggravation is the natural result of
the primary workplace injury or accident. Stated more precisely, the
claimant must establish that the subsequent aggravation is causally
linked to the primary compensable injury.‖49 The court cites to


   45Washington Cnty. Sch. Dist., 2013 UT App 205, ¶ 40 (alteration in
original) (quoting McKean, 706 P.2d at 602).
   46   Id. ¶ 43 (emphasis added).
   47   Id.
   48   Id. ¶ 44.
   49   2013 UT App 301, ¶ 12 (internal quotation marks omitted).

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                           Opinion of the Court
McKesson for this articulation of the rule. This statement of the rule,
while technically correct in that the two injuries must be causally
linked, appears to permit any causal link between the two injuries to
allow workers‘ compensation benefits for the subsequent non-
workplace injury. The appeals court in Oliver remanded for a
decision regarding the causal link between the two injuries.50
    ¶37 We take this opportunity to clarify the causal standard
required when an employee attempts to recover workers‘
compensation benefits for a subsequent non-workplace injury. We
hold that under the direct and natural results test, an employee must
establish that the initial workplace injury was a significant
contributing cause of the subsequent non-workplace injury, not
merely a cause or a minor cause. This standard is supported by the
plain language of the statute and our prior caselaw interpreting this
statute.
    ¶38 We recognize that it ―is the duty of the courts and the
commission to construe the Workers‘ Compensation Act liberally
and in favor of employee coverage when statutory terms reasonably
admit of such a construction.‖51 But the principle of liberal
construction is not unbounded.52 And we do not believe that the
legislature intended the ―arising out of‖ language to include any and
all subsequent injuries that are in any way causally connected to the
workplace injury, no matter how remote. Some meaningful level of
causal connection must be required; otherwise the employer
becomes the insurer for all subsequent injuries, even those only
minimally related to the initial workplace injury.
   II. We Decline to Adopt the School District‘s 50 Percent Causal
      Standard and Identify the Support for Our Standard in the
                 Approaches of Other Jurisdictions
   ¶39 In clarifying our standard, we decline the School District‘s
invitation to adopt a standard requiring a greater than 50 percent
causal connection between the two injurious events in order to
provide compensation. This standard is not supported by the plain
language of the Worker‘s Compensation Act. And, while the School

   50   Id. ¶ 14.
   51   Heaton v. Second Injury Fund, 796 P.2d 676, 679 (Utah 1990).
   52See Jex v. Utah Labor Comm’n, 2013 UT 40, ¶ 56, 306 P.3d 799
(holding that the liberal construction principle is invoked only in the
case where the usual process of interpretation ―yields genuine
doubt‖).

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                  WASHINGTON CNTY. v. LABOR COMM‘N
                              Opinion of the Court
District argues that a majority of jurisdictions take such an approach,
our survey revealed a much more nuanced picture—with states
applying a range of standards. Our research did, however, show that
our clarified standard is in line with how many jurisdictions address
this issue.
    ¶40 To begin, the 50 percent standard advanced by the School
District is not appropriate as it is not supported by the plain
language of the statute. If the legislature had intended a specific
percentage standard to be applied, it could have easily built one into
the statute.53 Instead, it broadly stated that injuries that ―aro[se] out
of and in the course of the employee‘s employment, wherever such
injury occurred‖ are compensable.54
   ¶41 Further, the School District asserts that a ―majority of courts
that employ this [natural results] standard . . . require that the causal
connection between the two accidents be supported by more than
50%.‖ But in its survey of the law it incorrectly conflates the standard
for determining causation of a non-workplace injury with the
amount of evidence required to prove this causal relationship. 55 Our

   53See, e.g., UTAH CODE § 78B-5-819(2)(a) (providing that ―[i]f the
combined percentage or proportion of fault attributed to all persons
immune from suit is less than 40%, the trial court shall reduce that
percentage or proportion of fault to zero and reallocate that
percentage or proportion of fault to the other parties‖).
   54   Id. § 34A-2-401(1).
   55 For instance, the School District cites Harris v. Russell Petroleum
Corp., 55 So. 3d 1225, 1231 (Ala. Civ. App. 2010), for the proposition
that Alabama has ―employed a preponderance of the evidence
standard in some cases and a clear and convincing standard in
others‖ when assessing the required causal connection. But Harris is
mainly a case about the evidentiary standard required to prove the
causal relationship, not the causal relationship itself. Appellees fail to
separate the evidentiary standard required by the court from the
causal-relationship analysis. The court in Harris does not announce a
clear standard for the causal connection, but does in numerous
places indicate that the causal connection required is not simply the
same standard the court requires for its evidentiary analysis. Id. at
1229−31. For example, the court states that ―an employee must . . .
establish medical causation by showing that the accident caused or
was a contributing cause of the injury‖ and that ―the dependent
[must] prove[] by clear and convincing evidence that the surgery
was necessitated by work-related cumulative trauma.‖ Id. at 1230,
                                                            (Continued)
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                          Cite as: 2015 UT 78
                         Opinion of the Court
survey of the states‘ approaches to the subsequent non-workplace
injury issue revealed a more nuanced picture, with states applying a
range of standards based on the ―arising out of language‖ in their
workers‘ compensation laws.
    ¶42 Generally, the states take one of two approaches when
interpreting this broad language. Some, like ours, require the
employee to prove that the subsequent non-workplace injury is
causally connected to the initial workplace injury.56 Within these
states many apply a standard similar to our clarified standard. Other
states provide compensation unless the employer can prove that
there was an independent intervening cause sufficient to break the
causal chain making the secondary non-workplace injury non-
compensable.57 In still other states, the legislature has acted to more
clearly address the subsequent injury situation.58
    ¶43 States that require a causal connection between the initial
workplace injury and the subsequent non-workplace injury define
this required causal relationship in a number of ways. A majority
have adopted Professor Larson‘s direct and natural results test,


1231 (first alteration in original) (emphasis added) (internal
quotation marks omitted).
   56 See, e.g., Harris, 55 So. 3d at 1230; Rodgers v. Workers’ Comp.
Appeals Bd., 214 Cal. Rptr. 303, 308 (Cal. Ct. App. 1985); Richardson v.
Robbins Lumber, Inc., 379 A.2d 380, 383 (Me. 1977); Pace v. City of St.
Joseph, 367 S.W.3d 137, 147 (Mo. Ct. App. 2012); Grable v.
Weyerhaeuser Co. (In re Grable), 631 P.2d 768, 776 (Or. 1981); Blackwell
v. Bostitch, 591 A.2d 384, 386 (R.I. 1991); Allen & Rocks, Inc. v. Briggs,
508 S.E.2d 335, 340 (Va. Ct. App. 1998).
   57 Although similar in application to the first standard mentioned
above, this analysis shifts the burden to the employer and serves as
an affirmative defense. To be relieved of liability, an employer must
demonstrate that some event independent of the workplace
triggered a claimant‘s disability entirely separate from the primary
workplace injury. See, e.g., Guidry v. J & R Eads Constr. Co., 669
S.W.2d 483, 485 (Ark. Ct. App. 1984); Linder v. City of Payette, 135
P.2d 440, 441 (Idaho 1943); Howard Indus., Inc. v. Robinson, 846 So. 2d
245, 257 (Miss. Ct. App. 2002); Mendoza v. Omaha Meat Processors, 408
N.W.2d 280, 286 (Neb. 1987); Whitfield v. Daniel Constr. Co., 83 S.E.2d
460, 462 (S.C. 1954).
   58 See, e.g., FLA. STAT. § 440.09(1) (2014); NEV. REV. STAT.
§ 616C.175(2) (2014); OR. REV. STAT. § 656.273 (2013).

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                 WASHINGTON CNTY. v. LABOR COMM‘N
                          Opinion of the Court
requiring a subsequent injury to be a ―direct and natural result‖ of
the primary injury.59 Many of these states have not fully defined the
causal connection necessary to allow for compensation—requiring
instead that the subsequent injury be the direct and natural
consequence without significant additional guidance.60 Some
jurisdictions have imported tort law principles into their analysis,
either through the use of a proximate cause analysis61 or through
apportionment.62 While a few jurisdictions do require a causal
connection of greater than 50 percent,63 others appear to require a de
minimus causal link, such as a ―but for‖ test.64


   59 See 1 LEX K. LARSON, LARSON‘S WORKERS‘ COMPENSATION LAW
§ 10.01D (2015) (citing jurisdictions that have adopted Larson‘s
―direct and natural consequences‖ language); see also Lou Grubb
Chevrolet, Inc. v. Indus. Comm’n, 846 P.2d 836, 839 (Ariz. Ct. App.
1992); Guidry, 669 S.W.2d at 485; Travelers Ins. Co. v. Savio, 706 P.2d
1258, 1265 (Colo. 1985); Sapko v. State, 44 A.3d 827, 842–43 (Conn.
2012); Diaz v. Oahu Sugar Co., 883 P.2d 73, 76–77 (Haw. 1994);
Addington Res., Inc. v. Perkins, 947 S.W.2d 421, 423 (Ky. Ct. App.
1997); Makin & Assocs. v. Harris, 672 A.2d 1110, 1112−13 (Md. 1996);
Schaefer v. Williamston Cmty. Schs., 323 N.W.2d 577, 582 (Mich. Ct.
App. 1982); Jackson v. Red Owl Stores, Inc., 375 N.W.2d 13, 18 (Minn.
1985); Oldham v. OK Iron & Metal, 996 P.2d 464, 467 (Okla. Civ. App.
1999).
   60 See, e.g., Travelers Ins. Co., 706 P.2d at 1265; Sapko, 44 A.3d at
842–43; Jackson v. Stevens Well Serv., 493 P.2d 264, 269 (Kan. 1972);
Addington Res., Inc., 947 S.W.2d at 423; Makin & Assocs., 672 A.2d at
1113; Jackson, 375 N.W.2d at 18; Rightnour v. Kare-Mor, Inc., 732 P.2d
829, 831 (Mont. 1987); In re Croteau, 658 A.2d 1199, 1203 (N.H. 1995);
Aragon v. State Corr. Dep’t, 824 P.2d 316, 319 (N.M. Ct. App. 1991);
Oldham, 996 P.2d at 467.
   61 See, e.g., Joseph E. Seagram & Sons, Inc. v. Willis, 401 N.E.2d 87, 90
(Ind. Ct. App. 1980); Lane v. S & S Tire, Inc., 182 S.W.3d 501, 505−06
(Ky. 2005); Paige v. City of Sterling Heights, 720 N.W.2d 219, 227
(Mich. 2006).
   62See Weaver v. Swedish Imps. Maint., Inc., 354 S.E.2d 477, 483−84
(N.C. 1987).
   63 See, e.g., FLA. STAT. § 440.09(1) (2014) (requiring that ―the
accidental compensable injury must be the major contributing cause
of any resulting injuries‖ and defining ―major contributing cause‖ as
―the cause which is more than 50 percent responsible for the injury
                                                         (Continued)
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                            Cite as: 2015 UT 78
                           Opinion of the Court
    ¶44 Though it is difficult to categorize the diverse approaches of
the states, our clarified standard is in line with the approach of
several jurisdictions.65 For instance, the Maine Supreme Court has
stated that ―the proper approach to the causation question requires
that the commissioner first determine whether a work-related injury
occurred. If that inquiry is answered in the affirmative, the critical
question then becomes whether the work-related injury remained a
substantial factor in causing the ultimate disability.‖66 Similarly, in
Missouri ―when work is a substantial factor in causing the medical
condition, every natural consequence that flows from the injury,
including a distinct disability in another area of the body, is
compensable as a direct and natural result of the primary or original
injury.‖67 Further, Rhode Island requires the ―first injury [to be] a
material contributing cause or a substantial factor in causing the
second injury.‖68
    ¶45 Also, legislatures that have directly addressed the
subsequent non-workplace injury issue have similarly defined the
causal standard. For instance, in Nevada the legislature requires
proof that the workplace injury was a ―substantial contributing
cause.‖69 The Nevada statute also shifts the burden to the insurer,
providing that the employee‘s subsequent aggravation of her injury
is compensable ―unless the insurer can prove by a preponderance of
the evidence that the [subsequent] injury . . . is not a substantial
contributing cause of the resulting condition.‖70 Similarly, in Oregon
the legislature has stated that worsening of a compensable injury is

as compared to all other causes combined for which treatment or
benefits are sought‖); Ball v. State ex rel. Wy. Workers’ Safety & Comp.
Div., 239 P.3d 621, 628 (Wyo. 2010).
   64 See, e.g., Global Prods. v. Workers’ Comp. Comm’n, 911 N.E.2d
1042, 1046 (Ill. App. Ct. 2009) (―So long as a ‗but-for‘ relationship
exists between the original event and the subsequent condition, the
employer remains liable.‖).
   65See Lou Grubb Chevrolet, Inc., 846 P.2d at 839; Richardson, 379
A.2d at 383; Pace, 367 S.W.3d at 146−47; Blackwell, 591 A.2d at 386.
   66   Richardson, 379 A.2d at 383 (citation omitted).
   67   Pace, 367 S.W.3d at 147 (internal quotation marks omitted).
   68   Blackwell, 591 A.2d at 386.
   69   NEV. REV. STAT. § 616C.175(2) (2014).
   70   Id.

                                      19
                  WASHINGTON CNTY. v. LABOR COMM‘N
                           Opinion of the Court
also compensable, but ―if the major contributing cause of the
worsened condition is an injury not occurring within the course and
scope of employment, the worsening is not compensable.‖71
    ¶46 We decline to adopt the 50 percent causal standard
advanced by the School District, as it is not supported by our statute
or caselaw. Further, it is not, as the School District has suggested,
how a majority of jurisdictions address this issue. Our clarified
standard—requiring the primary workplace injury to be a significant
contributing cause of the subsequent non-workplace injury—is
supported by the plain language of the Utah Worker‘s
Compensation Act and our prior caselaw. This standard is also in
line with how many jurisdictions interpret similar language in their
workers‘ compensation laws and how legislatures that have
addressed this issue have defined the required causal connection.
Because the standard applied by the court of appeals and the
Commission is inconsistent with our clarified standard, we remand
this case to the Commission to conduct this fact-intensive analysis
under the correct standard.72
   ¶47 As stated above, because we clarify the causation standard
and remand for additional proceedings, we do not address the issue
of whether the ALJ erred in not referring the case to a medical panel.
The ALJ will have to reconsider whether the medical evidence
presented creates a conflict under the clarified causal standard.
                                Conclusion
   ¶48 We clarify that our causal standard under the direct and
natural results test requires the employee to establish that the
primary workplace injury was a significant contributing cause of the
subsequent non-workplace injury in order to recover workers‘

   71   OR. REV. STAT. § 656.273(1) (2013).
   72  See Nelson v. State Tax Comm’n, 506 P.2d 437, 440 (Utah 1973)
(―It is within the inherent power, and the procedural rules of this
court, to order a new trial, or a further trial of material issues, when
the interests of justice so require; and this is equally true with respect
to the review of proceedings of administrative agencies.‖ (footnote
omitted)); see also McBride v. Motor Vehicle Div. of Utah State Tax
Comm’n, 1999 UT 9, ¶ 20, 977 P.2d 467 (remanding the case back to
the Commission to apply the correct legal standard to the facts of the
case); 1 LEX K. LARSON, LARSON‘S WORKERS‘ COMPENSATION LAW
§ 10.04 (2015) (recognizing that ―[d]ecisions in these sorts of cases are
necessarily fact driven‖).

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                       Cite as: 2015 UT 78
                      Opinion of the Court
compensation benefits for the subsequent injury. We therefore
remand the case back to the Commission to determine if
Mr. Brown‘s injury meets this standard. Because we remand the case
for further proceedings we do not address the medical panel issue.




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