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

                                 2020 UT 59

                                    IN THE

        SUPREME COURT OF THE STATE OF UTAH

                         NOE ARREGUIN-LEON,
                              Petitioner,
                                       v.
                    HADCO CONSTRUCTION, LLC,
                           Respondent.

                            No. 20190121
                       Heard February 10, 2020
                        Filed August 17, 2020

             On Certiorari to the Utah Court of Appeals

                      Fourth District, Provo
                  The Honorable Fred D. Howard
                         No. 130400816

                                 Attorneys:
Troy L. Booher, Beth E. Kennedy, Salt Lake City, Leonard McGee,
               Peter Mifflin, Sandy, for petitioner
         Robert L. Janicki, Michael L. Ford, Sandy, Harry Lee,
       Shannen W. Coffin, Mark C. Savignac, Washington D.C.,
                             for respondent

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

   JUSTICE PETERSEN, opinion of the Court:
                           INTRODUCTION
   ¶1 Noe Arreguin1 was injured while working on a highway
construction site. He sued Hadco Construction, LLC, the general
__________________________________________________________
   1 Although the plaintiff’s last name in the case caption is
Arreguin-Leon, we refer to him in this opinion as Arreguin
because that is how he refers to himself in his briefing.
         ARREGUIN-LEON v. HADCO CONSTRUCTION, LLC
                       Opinion of the Court

contractor, for failing to take necessary safety measures to protect
workers from highway traffic. Arreguin prevailed at trial. But
during trial, he elicited undisclosed testimony from his expert
witness. The court of appeals found this error to be harmful and
reversed and remanded for a new trial. We affirm.
                        BACKGROUND
    ¶2 Noe Arreguin was injured while installing an exit sign on
the shoulder of I-15. A driver fell asleep at the wheel and veered
off the road and into the ladder on which Arreguin was standing.
    ¶3 Arreguin worked for a company called Highway Striping
& Signs. The company had been hired by Hadco to install signage
for a Utah Department of Transportation roadway project in Utah
County. In its role as general contractor, Hadco was responsible
for implementing a “traffic control plan” composed of various
safety measures to protect workers from traffic and drivers from
the construction site. Hadco did not do so. At the time of the
accident, there were no traffic control measures in place at the
accident site, such as barrels or barriers.
    ¶4 As a result of the accident, Arreguin sustained significant
injuries. He sued the driver and Hadco (along with others who
are not relevant to this appeal).
    ¶5 Arreguin retained Bruce Reading as an expert witness on
traffic control standards. Hadco’s counsel elected to depose
Reading rather than receive an expert report.
    ¶6 The case proceeded to a jury trial, at which Arreguin
called Reading to testify. Reading opined that Hadco or its
subcontractor had violated five specific engineering practices,
regulatory standards, and contractual provisions and that there
was no traffic control plan in place at the accident site.
    ¶7 During direct examination, Arreguin’s counsel asked
Reading, “If [200 yards from the construction project is] where
[the driver] started to exit the roadway, what effect would a
correctly installed buffer zone have had on his driving?” Hadco’s
counsel objected and asked to approach the bench. The following
sidebar ensued:
      [DEFENSE COUNSEL]: Seems to me like this
      testimony is going toward causation—would traffic
      control have prevented the accident—and it goes
      beyond any opinion that he’s ever disclosed in this



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       case. There’s a list of his items of testimony, and he
       doesn’t touch on that at all.
       [PLAINTIFF COUNSEL]: Your Honor, Mr. Reading
       was deposed in this case. [Defense counsel] had
       every opportunity to ask any question he wanted,
       and—and he’s not limited to the initial disclosure. If
       he had—if [defense counsel] had elected a report, he
       would be limited to the contents of the report, but
       because a deposition has been elected, Mr. Reading
       is not so limited.
       [DEFENSE COUNSEL]: That’s not correct, your
       Honor.
       [PLAINTIFF COUNSEL]: And—and there were
       documents provided to Mr. Reading after
       (inaudible).
       [DEFENSE COUNSEL]: Then                he   needs   to
       supplement his disclosure.
       THE COURT: Your objection is noted and is,
       frankly, overruled.
       [DEFENSE COUNSEL]: Can I make a record—a
       record on this? I think it’s very important.
       THE COURT: This record is the record here now.
       [DEFENSE COUNSEL]: Okay. Thank you.
   ¶8 Reading then testified about the effect that a proper traffic
control plan would have had, including that if the accident
occurred where Hadco’s “safety person”2 suggested it did, it
would have been within a 900-foot area where the driver would
have hit “at least one, if not more, of th[e] plastic barrels” that
would have been in place. He explained that after hitting at least
one of the plastic barrels, the driver “would have had close to six
seconds to wake up and take corrective action.” And he
concluded that if traffic control had been in place, “[t]here might
have been an accident still,” but it would not have taken place
where it did.

__________________________________________________________
   2 At trial, Reading referred to Hadco’s “safety person.” From
the context, we understand this person to be the Hadco employee
who completed Hadco’s incident report about the accident.

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    ¶9 The trial continued and the jury ultimately found that
Hadco was partially liable for Arreguin’s injury. The jury
allocated 60 percent of the fault to the driver and 40 percent to
Hadco. Hadco appealed.
    ¶10 Approximately four months after filing its notice of
appeal, Hadco filed Reading’s deposition transcript and
Arreguin’s expert disclosures in the district court. They were
included in the record that was certified to the court of appeals.
    ¶11 One of Hadco’s arguments on appeal was that the district
court erred under Utah Rule of Civil Procedure 26 when it
allowed Reading to offer an undisclosed opinion on causation.
Arreguin argued that Hadco could not prevail on this argument
without relying on his expert disclosures and Reading’s
deposition transcript. But he asserted it was improper for the
court of appeals to consider these documents because they were
not actually part of the trial record.
   ¶12 The court of appeals decided to consider the disclosures
and the deposition transcript. It “acknowledge[d] that [Reading’s]
deposition was filed after the judgment was entered in this
matter, but before the record was prepared” and that “such filings
normally would not put the deposition before [the court of
appeals] for consideration.“ Arreguin-Leon v. Hadco Constr. LLC,
2018 UT App 225, ¶ 6 n.2, 438 P.3d 25. But it decided that “under
the unique facts of this case” it would “exercise [its] discretion
and consider the deposition.” Id.
   ¶13 The court of appeals concluded that the district court
abused its discretion in allowing Reading to testify about
causation at trial. Id. ¶ 20. And it determined that the error was
“harmful enough to warrant reversal and a new trial.” Id. ¶ 32.
    ¶14 Arreguin petitioned this court for certiorari, which we
granted to address three questions: (1) “[w]hether the Court of
Appeals erred in considering a deposition transcript that was not
included in the record prior to the filing of the appeal”;
(2) “[w]hether the Court of Appeals erred in construing [Hadco’s]
arguments on appeal to present a sufficient basis for its conclusion
that [Arreguin’s] expert testimony should have been excluded”;
and (3) “[w]hether the Court of Appeals erred in its construction
and application of the standard for demonstrating harmful error
on appeal.”
   ¶15 We have jurisdiction pursuant to Utah Code section
78A-3-102(3)(a).

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                    STANDARD OF REVIEW
    ¶16 “On certiorari, we review the court of appeals’ decision
for correctness, without according any deference to its analysis.”
Vander Veur v. Groove Entm’t Techs., 2019 UT 64, ¶ 7, 452 P.3d 1173
(citation omitted) (internal quotation marks omitted).
                            ANALYSIS
I. CONSIDERATION OF ARREGUIN’S EXPERT DISCLOSURES
      AND THE EXPERT’S DEPOSITION TRANSCRIPT
    ¶17 The first question before us is whether the court of
appeals erred in considering Arreguin’s expert disclosures and
Reading’s deposition transcript. Arreguin argues that the court of
appeals should not have considered these documents because
they were not truly part of the trial record, in that neither party
submitted either document for the district court’s consideration at
any point. Rather, Arreguin notes that Hadco filed the documents
five months after the district court entered the final judgment in
the case and four months after Hadco filed its notice of appeal.
    ¶18 We take Arreguin’s point. When the district court ruled
on Hadco’s objection, it did not actually have these documents
before it. The court of appeals decided to consider this
extra-record evidence because it determined Hadco’s counsel had
attempted to make a further record during the sidebar but had
been prevented from doing so by the district court. See
Arreguin-Leon v. Hadco Constr. LLC, 2018 UT App 225, ¶ 6 n.2, 438
P.3d 25. The court of appeals analogized this situation to one in
which a party is prevented from objecting, and thereafter should
not be prejudiced by the lack of an objection. See id.; see also UTAH
R. CIV. P. 46. Arreguin rejects this as a valid basis for considering
the extra-record materials.
    ¶19 We conclude that we do not need to resolve this dispute.
We can affirm the court of appeals’ ruling on the disputed expert
testimony without resort to the expert disclosures or deposition
transcript. Arreguin’s premise is that the content of these
documents is essential to Hadco’s argument—in other words, that
Hadco cannot successfully argue that the district court erred in
permitting Reading to testify about causation without relying on
the content of (1) the expert disclosures to prove that Arreguin did
not in fact disclose a causation opinion and (2) the deposition
transcript to prove that Hadco had “locked in” Reading to only
those opinions he offered during his deposition. But as we will
discuss, Arreguin never put the content of these documents at

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issue in the district court. Arreguin essentially contends that
Hadco must refute arguments he never made.
   ¶20 The court of appeals did rely upon the documents in its
reasoning, Arreguin-Leon, 2018 UT App 225, ¶ 23. But we disagree
with the premise that they are necessary to Hadco’s argument or
the court of appeals’ holding. As Hadco has argued, we can
resolve the rule 26 issue based solely on the transcript of the
sidebar between counsel and the district court at trial.
    ¶21 Looking only at the sidebar, we agree with the court of
appeals that the district court committed legal error in overruling
Hadco’s objection. During the sidebar, Hadco argued that
Arreguin’s question to Reading elicited a causation opinion,
which went “beyond any opinion that [Arreguin had] ever
disclosed in this case.” It is important to note Arreguin’s response.
He did not dispute Hadco’s assertion that his question would
elicit causation testimony. He did not assert that he had in fact
disclosed that Reading would offer a causation opinion or that
Reading had discussed causation in his deposition. And he did
not argue that Hadco had failed to “lock in” Reading to only the
opinions he had given at the deposition and therefore Reading
was free to offer additional opinions.
   ¶22 Instead, Arreguin asserted broadly that the expert was
not limited at all because Hadco had opted for a deposition rather
than an expert report. Arreguin’s counsel stated,
       Your Honor, Mr. Reading was deposed in this case.
       [Defense counsel] had every opportunity to ask any
       question he wanted, and—and he’s not limited to
       the initial disclosure. If he had—if [defense counsel]
       had elected a report, he would be limited to the
       contents of the report, but because a deposition has been
       elected, Mr. Reading is not so limited.
Hadco’s counsel responded, “That’s not correct, your Honor.”
With these arguments before it, the court overruled Hadco’s
objection and permitted the expert to offer the disputed
testimony.3


__________________________________________________________
   3 After this back-and-forth but before the court ruled, Arreguin
interjected that Hadco had provided documents to Reading after
the deposition. And Hadco countered, “[t]hen he needs to
                                                     (continued . . .)
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    ¶23 As the court of appeals correctly concluded, the district
court’s ruling was legally incorrect. Id. ¶ 26. Just because a party
opponent selects a deposition rather than an expert report does
not mean an expert’s subsequent trial testimony can be a
“free-for-all.” Id. ¶ 21.
    ¶24 In general, rule 26 provides that “discovery may be
obtained from an expert witness either by deposition or by
written report.” UTAH R. CIV. P. 26(a)(4)(B). With respect to a
written report, the rule makes clear that an expert is limited to
opinions disclosed in the report. Id. (“A report shall . . . contain a
complete statement of all opinions the expert will offer at trial and
the basis and reasons for them. Such an expert may not testify in a
party’s case-in-chief concerning any matter not fairly disclosed in
the report.”). The rule itself does not make a similar statement
with regard to an expert’s deposition. We generally agree with the
relevant advisory committee note, which explains that “[i]f a
party elects a deposition, rather than a report, it is up to the party
to ask the necessary questions to ‘lock in’ the expert’s testimony.”
Id. advisory committee note. In a case where an opposing party
fails to “lock in” an expert witness during the deposition, the
opposing party runs the risk of surprise testimony at trial.
   ¶25 However, this does not equate to the blanket assertion
advanced at trial by Arreguin that if Hadco “had elected a report,


supplement his disclosure.” Hadco’s response was legally correct.
See UTAH R. CIV. P. 26(d)(3)–(4); see also Arreguin-Leon v. Hadco
Constr. LLC, 2018 UT App 225, ¶ 23, 438 P.3d 25. And we do not
think that this additional exchange requires a review of the
content of the disclosures. Here too, Arreguin did not respond
that he had supplemented his disclosures or otherwise provided a
causation opinion at some point before trial. So he did not put the
content of his disclosures at issue.
   Arreguin asserts in his briefing to us that Hadco forfeited its
argument that Arreguin failed to supplement his disclosures.
Arreguin argues that although Hadco preserved this argument
during the sidebar, it did not raise the same argument in its
briefing to the court of appeals, so the argument has been waived.
However, Hadco has consistently asserted that Arreguin never
disclosed or produced, in any form or at any time before trial, a
causation opinion from Reading. Accordingly, we reject
Arreguin’s preservation argument.


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[Reading] would be limited to the contents of the report, but
because a deposition has been elected, Mr. Reading is not so
limited.” Arreguin’s counsel did not put the contents of the
disclosures or deposition at issue by asserting that a causation
opinion had in fact been disclosed at some point or that Hadco
had not properly “locked in” Reading at his deposition and
therefore he was free to offer new opinions at trial. Rather,
Arreguin made a very broad assertion to the district court that if a
party opponent elects to depose an expert witness, then the expert
witness is not limited during trial testimony. This is an incorrect
interpretation of rule 26(a)(4)(B), which the district court should
have rejected.
    ¶26 Accordingly, we agree with the court of appeals that the
district court should not have permitted Reading to offer the
disputed testimony based on the arguments before it. See id.
26(d)(4) (“If a party fails to disclose or to supplement timely a
disclosure or response to discovery, that party may not use the
undisclosed witness, document or material at any hearing or trial
unless the failure is harmless or the party shows good cause for
the failure.”). And we conclude that although the court of appeals
reviewed the disclosures and deposition and determined that
Arreguin had not disclosed a causation opinion and that Hadco
did in fact “lock in” Reading to the opinions he provided at the
deposition, this was not necessary to reach the correct legal result
because Arreguin had never argued otherwise.4
        II. UTAH RULE OF APPELLATE PROCEDURE 11
    ¶27 Although we do not need to reach the issue of whether
the court of appeals erred in considering the deposition transcript,
the parties’ briefing and oral argument did elucidate certain
ambiguities in Utah Rule of Appellate Procedure 11 that we flag
for our appellate rules advisory committee. The relevant portions
of rule 11 state,
       (a) Composition of the record on appeal. The
       original papers and exhibits filed in the trial court,

__________________________________________________________
   4 Arreguin also argues in his briefing to us that “because
Hadco did not make the documents part of the record, Hadco
could not show prejudice on appeal.” We are unsure how to
interpret this argument, and we are unable to resolve it because
Arreguin does not explain the argument further.

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                         Opinion of the Court

       . . . the transcript of proceedings, if any, the index
       prepared by the clerk of the trial court, and the
       docket sheet, shall constitute the record on appeal in
       all cases. . . . Only those papers prescribed under
       paragraph (d) of this rule shall be transmitted to the
       appellate court.
       ...
       (d)(2) Civil cases. Unless otherwise directed by the
       appellate court upon sua sponte motion or motion of
       a party, the clerk of the trial court shall include all of
       the papers in a civil case as part of the record on
       appeal.
       ...
       (h) Correction or modification of the record. If any
       difference arises as to whether the record truly
       discloses what occurred in the trial court, the
       difference shall be submitted to and settled by that
       court and the record made to conform to the truth. If
       anything material to either party is misstated or is
       omitted from the record by error, by accident, or
       because the appellant did not order a transcript of
       proceedings that the appellee needs to respond to
       issues raised in the Brief of Appellant, the parties by
       stipulation, the trial court, or the appellate court,
       either before or after the record is transmitted, may
       direct that the omission or misstatement be
       corrected and, if necessary, that a supplemental
       record be certified and transmitted.
UTAH R. APP. P. 11.
    ¶28 First, rule 11 references “the record” throughout, but it
does not define it. Rule 11(a) states that the “original papers and
exhibits filed in the trial court, . . . the transcript of proceedings, if
any, the index prepared by the clerk of the trial court, and the
docket sheet, shall constitute the record on appeal in all cases.” Id.
11(a) (emphasis added). It goes on to say that “only those papers
prescribed under paragraph (d) . . . shall be transmitted to the
appellate court.” Id. Rule 11(d)(2), which relates specifically to
civil cases, is quite broad. It states that the clerk “shall include all
of the papers in a civil case as part of the record.” Id. 11(d)(2). But
as illuminated here, there is ambiguity as to what “all of the
papers in a civil case” includes. Arreguin asserts that the record

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should include only those items that were actually presented in
court in some manner. However, the rule does not make explicit
that this is the case.
    ¶29 Next, rule 11(h) provides a mechanism for parties to
correct or modify the record. It states that, “[i]f any difference
arises as to whether the record truly discloses what occurred in
the trial court, the difference shall be submitted to and settled by
that court and the record made to conform to the truth.” Id. 11(h).
This has a clear meaning in some contexts—for example, if a
transcript inaccurately documents a witness’s testimony and can
be corrected by comparing the transcript to the audio recording of
the testimony, that would seem to make the record conform to the
truth. But in other contexts, the scope of what is meant by making
the record “conform to the truth” may not be entirely clear.
   ¶30 Finally, rule (11)(h) also permits modification of the
record “[i]f anything material to either party is misstated or is
omitted from the record by error” or “by accident.” But the rule
does not define either of these terms, and the scope of what might
be encompassed within them is not entirely clear.5
                     III. HARMLESS ERROR
   ¶31 Next, we must determine whether the court of appeals
erred in its construction and application of the standard for
demonstrating harmful error on appeal. We conclude it did not.
__________________________________________________________
   5  We also flag for our civil rules advisory committee a concern
raised by Arreguin’s counsel at oral argument regarding the court
of appeals’ treatment of Utah Rule of Civil Procedure 50(b). By
way of background, Arreguin argued in the court of appeals that
Hadco’s claims on appeal were unpreserved because Hadco had
not renewed its motion for directed verdict after trial, and
therefore had failed to meet the procedural requirements of rule
50(b). The court of appeals ultimately did not need to resolve this
argument but briefly addressed it in a footnote. See Arreguin-Leon
v. Hadco Constr. LLC, 2018 UT App 225, ¶ 29 n.9, 438 P.3d 25. At
oral argument before this court, counsel for Arreguin raised a
concern with this footnote. Because this issue is not before us, we
do not address it or opine one way or the other on the court of
appeals’ take on the rule. But we refer counsel’s concern to our
civil rules advisory committee for consideration.



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   ¶32 Arreguin argues that the court of appeals misapplied the
harmlessness standard, citing to the court of appeals’ statement
that it could not conclude “that the jury would have inevitably
reached the same result without Expert’s testimony.”
Arreguin-Leon v. Hadco Constr. LLC, 2018 UT App 225, ¶ 28, 438
P.3d 25. He contends that this is the incorrect standard.
    ¶33 Arreguin is correct that the cited sentence is not the
correct harmlessness standard. Rather, “[h]armless error is an
error that is sufficiently inconsequential that there is no
reasonable likelihood that it affected the outcome of the
proceedings.” H.U.F. v. W.P.W., 2009 UT 10, ¶ 44, 203 P.3d 943
(citation omitted). However, although the court of appeals used
the language Arreguin identifies, it does not appear to us that it
mistakenly thought this was the applicable legal standard. In the
preceding paragraph, the court of appeals correctly stated that
“[a]n error is harmful ‘only if the likelihood of a different outcome
is sufficiently high as to undermine our confidence in the
verdict.’” Arreguin-Leon, 2018 UT App 225, ¶ 27 (citation omitted).
This is substantively similar to the legal standard we identify
above. When the court used the disputed language, we agree with
Hadco that it was merely a shorthand reference to the legal
standard it had already identified. We see no legal error in the
court of appeals’ application of the law.
    ¶34 Arreguin also argues that the court of appeals erred when
it found the district court’s error to be harmful. He argues that
“expert testimony is not required to establish [the] obvious
proposition” that “if Hadco had set out the barrels to block traffic,
the driver would have hit at least one of them, woken up, and
taken corrective action” and “the barrels with sand in the bottom
likely would have prevented the driver from crashing into
[Arreguin].” Accordingly, he asserts that any error was harmless
because Reading’s testimony was “unnecessary and cumulative of
common sense” and “stated the obvious.”
    ¶35 We are not convinced. After the district court overruled
Hadco’s objection, Reading went beyond his testimony about the
components of a proper traffic safety plan and gave his opinion of
how such a safety plan would have changed the events that led to
Arreguin’s injury. Reading testified that if the driver drifted off
the road 200 yards back, he would have hit a barrel and “would
have been aware immediately upon impact” of the barrel. He
estimated that based on a two-and-a-half second reaction time, the
driver would have had “six seconds to wake up and take

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corrective action.” He then would have “jerk[ed] hard left.”
Ultimately, Reading opined that “[t]here might have been an
accident still. There’s no question about that. I don't think the
accident would have taken place where this happened.”
    ¶36 We think this testimony goes beyond common sense. A
lay juror could be expected to understand the gist of Reading’s
causation opinion—that the sleeping driver might hit a barrel,
wake up, and attempt a correction. But a layperson would not
necessarily understand with such precision the effect of a traffic
safety plan upon the events in question. And even if a layperson
might have assumed that “the accident would [not] have taken
place where this happened,” this opinion carried extra weight
because it came from an expert. We agree with the court of
appeals’ observation that Reading’s testimony “carried the
imprimatur of coming from an ‘expert,’” and it “provided a
logical roadmap that the jury could—and likely did—follow in
deciding the issues of liability and in apportioning fault.” Id. ¶ 28.
   ¶37 Arreguin also argues that the error was harmless because
Reading’s testimony was cumulative of testimony given by other
witnesses. But we do not view the testimony from the other
witnesses to be equivalent to Reading’s causation testimony.
    ¶38 Arreguin argues that Reading’s testimony that the
sleeping driver would have hit a barrel was duplicative of
testimony from Hadco’s expert. But this is not so clear. Reading
testified that given the parameters suggested by Hadco’s “safety
person,” the driver “would have [hit][6] at least one, if not more, of
these plastic barrels.” In comparison, Hadco’s expert testified
about calculating tapers and spacing of traffic control devices, but
he did not say that the sleeping driver would have hit a barrel.
The closest Hadco’s expert came to saying this was noting that a
traffic control device is an “indicator” and that barrels are “not
going to stop a vehicle from departing the roadway,” while
agreeing that they would “notify.” Reading’s testimony was more
specific and certain, and it was not cumulative of the testimony
from Hadco’s expert.



__________________________________________________________
   6 The transcript says this word was inaudible. From the context
of the sentence, it appears that the word was “hit” or another
synonymous word.

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    ¶39 Arreguin also argues that Reading’s testimony that
hitting the barrel would have awakened the driver was
cumulative of testimony from Hadco’s expert, Hadco’s project
manager, and the driver. Reading opined that hitting a barrel
would lead to a “hellacious sound” that is “going to wake him
up.” In contrast, when asked “if striking a barrel can be a jolting,
noisy experience,” Hadco’s expert responded, “Well, yes.” He
then commented, “I can’t say, if someone is already asleep,
though, if that would be something that would necessarily wake
them up.” When asked, “Would you agree that it is possible that
there was a barrel on the side of the road and [the driver] hit it as
he was going off the road, that it may have alerted him,” Hadco’s
expert responded, “It could have. I mean, I—I would be
speculating, but yeah. I couldn’t say specifically that it would, but
it may have.” Hadco’s project manager agreed that barrels need to
be “crashworthy.” And the driver testified that he woke up when
he heard “the grids in the road.” Arreguin argues that based on
this testimony, the jury could infer that if a rumble strip
awakened the driver, hitting a barrel also would have awakened
him. While that might be a fair inference, we disagree with
Arreguin’s assertion that Reading’s testimony is merely
duplicative of the other witnesses’ testimony. Again, Reading’s
testimony was specific and certain, while the testimony of the
other witnesses was equivocal or required an inferential leap.
    ¶40 Arreguin next argues that Reading’s testimony that the
driver would have taken corrective action also came from Hadco’s
expert and the driver. Again, Hadco’s expert testified about
calculating tapers and spacing of traffic control devices. He did
not clearly state that the driver would have taken corrective
action. Similarly, the driver testified that upon waking up and
seeing a flatbed truck in front of him he “swerved off to the side
to avoid it.” Neither is equivalent to Reading’s testimony that the
driver “would have had close to six seconds to wake up and take
corrective action,” that “the normal experience is you jerk hard
left to get back on,” and finally that “[t]here might have been an
accident still,” but he did not “think the accident would have
taken place where this happened.”
    ¶41 Reading’s disputed testimony related to the important
questions of whether and to what extent Hadco’s failure to
implement a proper traffic control plan on the day of the accident
caused Arreguin’s injuries. While other witnesses made
statements from which the jury could possibly have inferred the
disputed facts and opinions Reading provided, none of them gave

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testimony that was equivalent to Reading’s. None of the other
witnesses’ testimony on the disputed points was as clear, specific,
and emphatic as Reading’s. We agree with the court of appeals
that the district court’s error was not harmless. The erroneously
admitted testimony was not “sufficiently inconsequential that
there is no reasonable likelihood that it affected the outcome of
the proceedings.” See H.U.F., 2009 UT 10, ¶ 44 (citation omitted).
                         CONCLUSION
    ¶42 We agree with the court of appeals that the district court
abused its discretion in allowing Reading to offer causation
testimony. This error was harmful. We affirm the court of appeals’
decision, and we remand to the district court for a new trial.




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