               IN THE SUPREME COURT OF IOWA
                              No. 12–1192

                          Filed February 7, 2014


DENNIS H. HAGENOW and ROSALEE A. HAGENOW,

      Appellants,

vs.

BETTY L. SCHMIDT,

      Appellee.



      On review from the Iowa Court of Appeals.



      Appeal from the Iowa District Court for Black Hawk County,

David F. Staudt, Judge.



      Plaintiffs appeal from judgment on defense verdict in rear-end

collision.   DECISION OF COURT OF APPEALS VACATED; DISTRICT

COURT JUDGMENT AFFIRMED.



      James W. Carney and George W. Appleby V of Carney & Appleby,

P.L.C., Des Moines, for appellants.



      Samuel C. Anderson of Swisher & Cohrt, P.L.C., Waterloo, for

appellee.
                                     2

WATERMAN, Justice.

      In this appeal, we revisit the doctrine of legal excuse and the

sudden emergency defense, as applied to a rear-end collision the jury

could have found was caused by defendant’s stroke and resulting partial

loss of vision. Plaintiffs’ truck was stopped at a red light in good weather

when it was struck by defendant’s car. Defendant saw the red light but

denied seeing plaintiffs’ vehicle. At the emergency room she noticed she

could not see to her left. Testing confirmed she had suffered a stroke

that caused a partial loss of vision.     Defendant’s treating neurologist
initially noted that it was unclear whether the stroke occurred before or

after the accident.   Two months before trial, defendant disclosed the

neurologist would testify the stroke preceded the accident.

      Over plaintiffs’ objections, the district court allowed defendant’s

neurologist to testify and submitted the defense of sudden emergency.

The jury found the defendant was not negligent. The court of appeals

concluded the evidence supported a defense of legal excuse, but reversed

the judgment and remanded the case for a new trial based on erroneous

wording in the sudden emergency instruction. We granted defendant’s

application for further review and ordered supplemental briefing on the

applicability of the Restatement (Third) of Torts: Liability for Physical and

Emotional Harm, sections 9, 11, and 15—which address sudden

emergency, physical incapacitation, and legal excuse—and on whether

the jury instructions given were consistent with those provisions.

      For the reasons that follow, we conclude that the district court

acted within its discretion in allowing the defendant’s expert medical

testimony and that the evidence was sufficient to submit a legal-excuse
defense based on defendant’s sudden medical emergency.           We further

conclude any error in the wording of the instruction was harmless. We
                                    3

therefore defer to future cases our consideration of the foregoing

provisions of the Restatement (Third).    We vacate the decision of the

court of appeals and affirm the district court judgment for defendant.

      I. Background Facts and Proceedings.

      We view the evidence in the light most favorable to the jury verdict.

Condon Auto Sales & Serv., Inc. v. Crick, 604 N.W.2d 587, 593 (Iowa

1999).   On November 10, 2008, Betty Schmidt, then age seventy-five,

was in her first car accident, which ended her driving career. Schmidt

was returning home alone from grocery shopping, driving her 1999 Buick
LeSabre east on University Avenue in Cedar Falls at about 1:30 p.m.

The weather was clear and the roads were dry.         Schmidt, who wore

trifocals, had perceived no problem with her vision or health that would

impair her driving. She was feeling fine and had no trouble shopping or

driving before she reached the intersection with Cedar Heights Drive.

She planned to turn right there and saw the traffic light was red. But,

she did not see the pickup truck stopped in the right turn lane, Dennis

Hagenow’s 2008 GMC Sierra. Schmidt drove into the rear of Hagenow’s

truck, lodging her vehicle under his.    The impact deployed Schmidt’s

airbags. Both vehicles suffered disabling damage—Hagenow’s truck was

later deemed totaled—and were towed from the scene.          A responding

police officer asked Schmidt at the scene if she had been drinking, and

she answered “no.” She submitted to a Breathalyzer test, which detected

no alcohol. The officer cited Schmidt for failing to stop in an assured

clear distance.

      Schmidt was taken by ambulance to the Sartori Hospital

Emergency Room. An hour after arriving, while lying on an emergency
room cart, Schmidt realized she was unable to see someone who was

speaking to her. She alerted medical staff that she could not see to her
                                    4

left side.   After a CT scan at 3:15 p.m. and an MRI at 4:44 p.m.,

Dr. Daniel Miller diagnosed Schmidt’s condition as left homonymous

hemianopsia, which is the absence of vision in the left side of each eye.

This condition is a result of an injury to the brain that affects how a

person processes visual information.    Dr. Miller referred Schmidt to a

neurologist, Dr. Ivo Bekavac, who concluded Schmidt suffered an acute

ischemic infarct, commonly referred to as a stroke, in the right occipital

lobe of her brain and that this stroke caused Schmidt’s vision loss.

Dr. Bekavac noted in Schmidt’s chart, “It is not clear whether [the stroke]
happened before or after the accident.”    Schmidt had never previously

suffered a stroke.

      Schmidt remained at Sartori Hospital until November 18, when she

was transferred to Covenant Hospital for stroke rehabilitation services.

That day, her rehabilitation doctor, Dr. Barbara Malicka-Rozek, noted in

Schmidt’s file, “It was believed she probably had [a transient ischemic

attack] versus [a] stroke during driving, and this is how she lost control

of her vehicle.” Dr. Malicka-Rozek also commented, “Betty was admitted

. . . following a motor vehicle accident that likely occurred following a

[transient ischemic attack] or a stroke.” Schmidt was discharged from

Covenant on November 26. Because of her vision loss, she was no longer

able to drive.

      Dennis and his wife, Rosalee Hagenow, filed a personal injury

action against Schmidt on November 1, 2010.        On February 9, 2011,

Schmidt filed an answer denying negligence and pleading these

affirmative defenses:

      1.     Defendant was confronted by a sudden medical
             emergency, not of her own making, providing her with
             a legal excuse for any failure to observe the
                                     5
             requirements of any statute, ordinances, or common
             law duties concerning the operation of her vehicle.
      2.     The sole cause of the accident was an act of God in the
             form of an unexpected medical emergency.

On April 6, Schmidt served answers to the Hagenows’ interrogatories that

described her limited recollection of the accident.      She answered the

“expert” interrogatory by stating, “We have not retained any expert

witnesses for purposes of testifying at the time of trial. We do expect the

need to call as an expert witness my treating physicians who will testify

to my medical condition at the time of the accident.”           She named

Dr. Bekavac as one of her physicians.        Meanwhile, the district court

entered a scheduling order that set the jury trial for May 1, 2012. The

order required the plaintiffs to disclose experts no later than 210 days

before trial and defendant to do so 150 days before trial.

      On November 29, 2011, Schmidt served a “Designation of experts”

that stated her intent to call as an expert at the time of trial, “[t]reating

physician, Dr. Ivo Bekavac.” The designation also stated she “reserve[d]

the right to call [her] other treating physicians and elicit expert testimony

from them . . . at trial.”

      The Hagenows received Dr. Bekavac’s medical records that
autumn. The Hagenows’ counsel wrote to Schmidt’s counsel asserting

Dr. Bekavac’s comment, “It is not clear whether [the stroke] happened

before or after the accident,” established Schmidt would be unable to

prove her stroke occurred prior to the accident.         Schmidt’s counsel

responded on February 21, 2012, explaining:

      When I asked Dr. Bekavac about this statement, he said he
      made it because there is no way to know with 100%
      certainty as to when on November 10, 2008 the actual stroke
      occurred. However, he told me it is his belief that the stroke
      most likely preceded the accident.
                                    6

      On February 24, Schmidt filed a motion for summary judgment

with an affidavit attached from Dr. Bekavac. The affidavit acknowledged

his previous notation regarding the uncertainty as to the sequence of

Schmidt’s stroke and accident, but clarified:

      [I]t is my belief, from the information available to me, that
      the stroke most likely preceded the accident. The reason for
      my belief is that the medical evidence does not indicate that
      the automobile accident was a precipitating cause of
      Ms. Schmidt’s stroke. There is no sign of head trauma
      caused by the accident. It is significant that Ms. Schmidt
      reported that she did not lose consciousness but did not see
      the vehicle ahead of her. If, in approaching the intersection,
      Ms. Schmidt looked to her right in preparation of a right
      turn at the intersection, everything straight ahead of her in
      the left part of her visual field would have disappeared and
      Ms. Schmidt would not necessarily have perceived her
      sudden loss of this half of her vision field. The fact that she
      did not lose consciousness but did not see the vehicle ahead
      of her would be consistent with her having a stroke in
      advance of the accident. The fact that Ms. Schmidt first
      reported the loss of vision after she was in the emergency
      room for a period of time would make sense and would not
      change my opinion. The stroke happens quickly and can
      happen painlessly and she would not likely have known she
      was having a stroke or that she had lost part of her vision as
      the stroke occurred because she would still have had
      binocular vision through the right half of her visual field.
      Immediately after the accident, during the stress of the
      event, it would not be surprising that she would not notice
      she had lost the left side of her vision. It makes sense that
      following the accident, after the stress of the accident starts
      to die off and she is stationary in an emergency room,
      looking about the room, that she would begin noticing her
      loss of vision.
            In conclusion, it is my professional opinion to a
      reasonable degree of medical certainty that Ms. Schmidt
      suffered an acute right occipital infarct on November 10,
      2008 and that it is more probable than not that the stroke
      occurred immediately preceding the automobile accident.

      On March 5, the Hagenows designated a rebuttal expert, Dr. David

Friedgood. The same day, the Hagenows filed a resistance to Schmidt’s
motion for summary judgment and cross-motion for partial summary

judgment on liability, and a motion to exclude Dr. Bekavac’s testimony
                                    7

on grounds of late disclosure. The court held an unreported hearing on

March 21.   At that hearing, the court orally advised counsel it would

allow Dr. Bekavac to testify and directed the parties to cooperate in

scheduling depositions of Drs. Bekavac and Friedgood before trial. On

March 29, the Hagenows filed a motion to reconsider and, on April 16,

filed a motion in limine seeking the exclusion of Dr. Bekavac’s testimony.

Attached to this motion was an affidavit from Dr. Friedgood, which

opined that Schmidt suffered her stroke one hour after the accident,

while she was in the emergency room.
      On April 17, the district court filed written orders denying the

Hagenows’ motions to exclude Dr. Bekavac’s testimony.          The court

stated:

      This is not a case where the plaintiffs were unaware of the
      existence of an expert. This is also not a case in which the
      plaintiffs were unaware the treating physician had a
      professional medical opinion. This is merely a case in which
      the treating physician, for whatever reason, now has a
      different opinion than the opinion he expressed earlier.

The district court acknowledged the timing was “unfortunate,” but

pointed out that Schmidt had informed the Hagenows of Dr. Bekavac’s

changed opinion more than thirty days prior to trial, as required by Iowa

Rule of Civil Procedure 1.508(3). The district court offered the Hagenows’

counsel a continuance “should he determine he is unable to adequately

prepare and obtain the necessary expert opinion prior to trial in May.”

Dr. Bekavac was deposed on April 9, and Dr. Friedgood was deposed on

April 25.

      On April 26, the district court denied both parties’ motions for

summary judgment.      The district court noted that Dr. Bekavac and
Dr. Friedgood presented conflicting opinions regarding the timing of
                                     8

Schmidt’s stroke, and therefore, the court found Schmidt’s sudden

emergency defense presented a genuine issue of material fact.

      The Hagenows did not request a continuance, and trial began

May 1, as scheduled. Schmidt testified that she was living independently

at the time of the accident and drove nearly every day. She believed she

was in fine health on the day of the accident and had no reason to know

she would suffer a stroke that day.      Her memory of the accident and

subsequent events was incomplete. Though she did not remember her

speed, she testified that she had a practice of driving a little under the
speed limit.   She recalled approaching the red light and preparing to

signal a right-hand turn. The last thing she remembered “was seeing the

red light at the intersection and thinking I needed to stop.” She testified

she did not remember seeing the Hagenows’ truck stopped in front of her

at the intersection, nor did she remember the impact or her airbags going

off. She did, however, recall speaking with the police officer at the scene.

She also remembered speaking with a medical responder, though she did

not remember her resulting trip to the emergency room in an ambulance.

Despite her spotty memory, Schmidt denied that she lost consciousness.

      Drs. Bekavac and Friedgood testified by deposition.              They

disagreed whether Schmidt’s stroke occurred before or after the accident.

Dr. Bekavac testified that Schmidt’s stroke preceded the accident, while

Dr. Friedgood testified the stroke occurred in the emergency room at the

time Schmidt noted her vision loss. But, the experts agreed on a number

of issues.     Both experts agreed Schmidt suffered a stroke on

November 10, 2008.       Both experts agreed the right occipital lobe

processes the information from one’s left visual field. Both agreed that,
because of the stroke, Schmidt suffered homonymous hemianopsia and
                                     9

lost half of her visual field. Both agreed Schmidt would not have been

able to drive her car successfully with that condition.

      Moreover, both agreed that what Schmidt could see depended on

how she had her head or eyes turned.         Dr. Bekavac explained that, if

Schmidt was looking at his face and he held his hand to her left side, she

would be unable to see his hand. Dr. Friedgood stated that, if Schmidt

was looking straight forward, she would only “see” from her nose over to

her right.    Dr. Bekavac noted that, due to this phenomenon, Schmidt

would be unable to see a car directly ahead of her if she were looking
even three-quarters to her right.        Schmidt herself gave examples to

illustrate the extent of her vision loss, noting she has difficulty reading

because she can see only the right half of the page of a book when

viewing it straight ahead. She explained that she can only see half of a

dinner plate on a table while eating and noted that she had knocked over

her drink several times lately because it was placed to the left side of her

plate. Nevertheless, Schmidt does not “see blackness” in the left half of

her vision.    As Dr. Friedgood explained, no one can see 360°.      Yet, a

person does not see blackness for the 180°; they simply do not “see”

anything.

      Schmidt proposed jury instructions regarding sudden emergency

and legal excuse. The Hagenows objected to submission of the sudden

emergency defense, arguing no factual foundation existed for the

instructions because no expert testified to a reasonable degree of medical

certainty that Schmidt suffered a stroke that rendered her incapable of

operating a vehicle.     The Hagenows also argued that, if a sudden

emergency instruction was provided, “there should be a specific
requirement that the jury find [the stroke caused the] impairment to

Betty Schmidt to the extent that she could not operate her motor
                                           10

vehicle.”    The district court overruled the Hagenows’ objections and

declined their request to provide causation language within the sudden

emergency instruction.1

       At Schmidt’s request, the district court submitted an instruction

modeled after Iowa Civil Jury Instruction 600.75.2                   This instruction,

No. 19, stated:

             A sudden emergency is an unforeseen combination of
       circumstances that calls for immediate action or a sudden or
       unexpected occasion for action. A driver of a vehicle who,
       through no fault of her own, is placed in a sudden
       emergency, is not chargeable with negligence if the driver
       exercises that degree of care which a reasonably careful
       person would have exercised under the same or similar
       circumstances.

For Instruction No. 20, the district court submitted an instruction based

upon Iowa Civil Jury Instruction 600.74,3 as proposed by Schmidt. This

instruction stated:




       1The Hagenows do not appeal the district court’s refusal to include their

requested causation language within the instruction.
       2Uniform   instruction 600.75, captioned “Sudden Emergency,” states:
       A sudden emergency is an unforeseen combination of circumstances that
       calls for immediate action or a sudden or unexpected occasion for action.
       A driver of a vehicle who, through no fault of [his] [her] own, is placed in
       a sudden emergency, is not chargeable with negligence if the driver
       exercises that degree of care which a reasonably careful person would
       have exercised under the same or similar circumstances.
Iowa State Bar Ass’n, Iowa Civil Jury Instructions 600.75 (2012).
       3Uniform   instruction 600.74, captioned “Legal Excuse,” states:
       (Name) claims that if you find that [he] [she] violated the law in the
       operation of [his] [her] vehicle, [he] [she] had a legal excuse for doing so
       because (excuse) and, therefore, is not negligent. “Legal excuse” means
       that someone seeks to avoid the consequences of [his] [her] conduct by
       justifying acts which would otherwise be considered negligent. The
       burden is upon (name) to establish as a legal excuse:
              1. Anything that would make complying with the law impossible.
                                           11
             Betty Schmidt claims that if you find that she violated
       the law in the operation of her vehicle, she had a legal
       excuse for doing so because of a sudden medical emergency
       and, therefore, is not negligent. “Legal excuse” means that
       someone seeks to avoid the consequences of his or her
       conduct by justifying acts which would otherwise be
       considered negligent. The burden is upon Betty Schmidt to
       establish as a legal excuse:
             1. That Betty Schmidt had no control over the sudden
       medical emergency she alleges occurred which placed her
       vehicle in a position contrary to the law.
             2. That her failure to obey the law when she was
       confronted with a sudden medical emergency was not a
       circumstance of her own making.
             If you find that Betty Schmidt has violated the law as
       submitted to you in other instructions and that she has
       established a legal excuse for doing so under either of the
       two definitions set forth above, then you should find that
       Betty Schmidt was not negligent for violating the particular
       law involved.

       On May 7, 2012, the jury returned a verdict in favor of Schmidt,

answering “no” to the first question, “Was the defendant, Betty Schmidt,

at fault?”

       The Hagenows moved for a judgment notwithstanding the verdict

or new trial, arguing Schmidt “failed to prove there was a stroke that

transpired prior to the collision in question and most importantly that

the stroke in any manner impaired Mrs. Schmidt in the operation of her


______________________
               2. Anything over which the driver has no control which places
       [his] [her] vehicle in a position contrary to the law.
             3. Failure to obey the law when the driver is confronted with
       sudden emergency not of [his] [her] own making.
              4. An excuse or exception provided by the law.
               If you find that (name) has violated the law as submitted to you in
       other instructions, and that [he] [she] has established a legal excuse for
       doing so under any one of the four definitions set forth above, then you
       should find that (name) was not negligent for violating the particular law
       involved.
Iowa State Bar Ass’n, Iowa Civil Jury Instructions 600.74.
                                       12

vehicle.” The district court denied this motion. The Hagenows appealed,

arguing the district court erred in failing to exclude Dr. Bekavac’s

testimony and in instructing the jury on sudden medical emergency. We

transferred the case to the court of appeals. In its opinion, the court of

appeals stated:

         Because there was testimony, albeit disputed testimony, that
         Schmidt experienced a stroke depriving her of her left visual
         field before the accident, we believe an instruction as to legal
         excuse was warranted by the evidence—if Schmidt was
         unable to see Hagenow’s vehicle, it would have been
         impossible or beyond her control to have stopped behind
         him.

(Emphasis added.) But, the court of appeals further concluded “the type

of legal excuse warranted by the evidence was not included in the

instructions given.” Focusing on the language in the sudden emergency

instruction that “calls for immediate action or a sudden or unexpected

occasion for action,” the court of appeals queried, “if Schmidt did not

know she had a stroke or lost a portion of her visual field, what action

was called for under the circumstances?”            Based on this perceived

disconnect between the language of the instruction and the facts, the

court of appeals held the sudden emergency instruction was “neither
applicable nor supported by the evidence.”             The court of appeals

therefore reversed the judgment in favor of Schmidt and ordered a new

trial.    Because the court of appeals found the jury instruction issue

dispositive, it did not decide whether the district court abused its

discretion by allowing Dr. Bekavac to testify.

         We granted Schmidt’s application for further review.

         II. Scope of Review.

         We review for abuse of discretion discovery rulings on whether to
exclude evidence as a sanction for untimely disclosure. Whitley v. C.R.
                                    13

Pharmacy Serv., Inc., 816 N.W.2d 378, 385 (Iowa 2012). “[W]e will not

reverse the court’s decision to admit evidence unless the record shows

prejudice to the complaining party.” Id. We likewise review for abuse of

discretion rulings allowing or disallowing expert testimony challenged as

untimely and “accord the trial court broad discretion.” Klein v. Chi. Cent.

& Pac. R.R., 596 N.W.2d 58, 60–61 (Iowa 1999) (affirming district court’s

exclusion of opinion testimony of company physician due to late

disclosure). “An abuse of discretion consists of a ruling which rests upon

clearly untenable or unreasonable grounds.” Lawson v. Kurtzhals, 792
N.W.2d 251, 258 (Iowa 2010).

      “We review a claim that the district court gave an instruction not

supported by the evidence for correction of errors at law.”     Pavone v.

Kirke, 801 N.W.2d 477, 494 (Iowa 2011). “We review the related claim

that the trial court should have given [a party’s] requested instructions

for an abuse of discretion.”   Crawford v. Yotty, 828 N.W.2d 295, 298

(Iowa 2013) (internal quotation marks omitted). “We evaluate the alleged

instructional error from the perspective that a trial court is generally

required to give a requested instruction ‘when it states a correct rule of

law having application to the facts of the case.’ ” Pexa v. Auto Owners

Ins. Co., 686 N.W.2d 150, 160 (Iowa 2004) (quoting Stover v. Lakeland

Square Owners Ass’n, 434 N.W.2d 866, 868 (Iowa 1989)).

      We will affirm the submission of an instruction if substantial

evidence supports it.   See Jones v. Blair, 387 N.W.2d 349, 352 (Iowa

1986). “Substantial evidence is that which a reasonable person would

find adequate to reach a conclusion.” Greenwood v. Mitchell, 621 N.W.2d

200, 204 (Iowa 2001) (internal quotation marks omitted). In reviewing
whether a sudden emergency instruction was properly submitted, we

view the evidence in the light most favorable to the party asserting the
                                              14

defense. Weiss v. Bal, 501 N.W.2d 478, 481 (Iowa 1993); see also Blair,

387 N.W.2d at 352. “Error in giving or refusing to give a jury instruction

does not warrant reversal unless it results in prejudice to the

complaining party.” Koenig v. Koenig, 766 N.W.2d 635, 637 (Iowa 2009)

(internal quotation marks omitted). “Instructions must be considered as

a whole, and if the jury has not been misled there is no reversible error.”

Thavenet v. Davis, 589 N.W.2d 233, 236 (Iowa 1999).

     III. Whether the District Court Abused Its Discretion by
Allowing Dr. Bekavac to Testify on Causation.

       The     Hagenows       argue     the    district   court     erred    in   allowing

Dr. Bekavac’s expert opinion testimony—disclosed sixty-seven days

before trial—that Schmidt’s stroke occurred before the accident.                      They

argue Schmidt failed to timely supplement her discovery responses on

expert testimony as required by Iowa Rule of Civil Procedure 1.508(3).4

We conclude the district court did not abuse its discretion by allowing

Dr. Bekavac’s expert medical opinion because Schmidt disclosed his

opinion more than two months before trial and the Hagenows suffered no

unfair prejudice. Specifically, the Hagenows declined a continuance and

       4A    treating physician may become subject to expert disclosure requirements
when his trial testimony is based on “factual knowledge, mental impressions and
opinions . . . ‘acquired or developed in anticipation of litigation or for trial.’ ” Day v.
McIlrath, 469 N.W.2d 676, 677 (Iowa 1991). Moreover, if a “treating physician assumes
a role in litigation analogous to the role of a retained expert, supplemental discovery . . .
could become obligatory.” Id. Dr. Bekavac testified on causation, specifically, that
Schmidt’s stroke preceded the accident and explains her failure to see the Hagenow
vehicle. His 2012 trial testimony thereby went beyond his diagnosis and treatment of
her stroke in 2008. We conclude Dr. Bekavac’s opinion on causation was subject to the
disclosure and supplementation requirements of Iowa Rule of Civil Procedure 1.508
governing experts. Cf. Hansen v. Cent. Iowa Hosp. Corp., 686 N.W.2d 476, 484 (Iowa
2004) (holding physician “was not within the ambit of [Iowa Code] section 668.11,”
which governs expert disclosures in professional malpractice cases, when his opinion
on causation was formed treating the plaintiff). Schmidt indeed formally designated
Dr. Bekavac as an expert witness on November 29, 2011, complying with the deadline
to disclose defense experts 150 days before the trial set for May 1, 2012.
                                   15

had time to depose Dr. Bekavac and obtain a rebuttal expert,

Dr. Friedgood, before trial.

      Rule 1.508 governs “Discovery of experts.” Rule 1.508(1)(a)

provides:

      A party may through interrogatories require any other party
      . . . to state, with reasonable particularity, all of the
      following:
             (1) The subject matter on which the expert is expected
      to testify.
            (2) The designated person’s qualifications to testify as
      an expert on such subject.
            (3) The mental impressions and opinions held by the
      expert and the facts known to the expert (regardless of when
      the factual information was acquired) which relate to, or
      form the basis of, the mental impressions and opinions held
      by the expert.

Iowa R. Civ. P. 1.508(1)(a).

      Rule 1.508(3) addresses when supplemental discovery is required,

and provides in full:

      If a party expects to call an expert witness . . . when the
      substance of an expert’s testimony has been updated, revised
      or changed since the response, such response must be
      supplemented to include the information described in rule
      1.508(1)(a)(1) to (3), as soon as practicable, but in no event
      less than 30 days prior to the beginning of trial except on
      leave of court. If the identity of an expert witness and the
      information described in rule 1.508(1)(a)(1) to (3) are not
      disclosed or supplemented in compliance with this rule, the
      court in its discretion may exclude or limit the testimony of
      such expert, or make such orders in regard to the
      nondisclosure as are just.

Id. r. 1.508(3) (emphasis added).        This rule required Schmidt to

supplement her discovery responses to disclose Dr. Bekavac’s opinion

that the stroke preceded the accident.

      Compliance with both the “as soon as practicable” and the “thirty
day” requirements is necessary, as “the two requirements are cumulative
                                    16

so that violation of either amounts to noncompliance.”        Stephenson v.

Furnas Elec. Co., 522 N.W.2d 828, 831 (Iowa 1994). “Consistent with the

discovery rules in general, the duty to supplement seeks to clarify issues

prior to trial, avoid surprise to parties, and allow a complete opportunity

to prepare for trial.” Whitley, 816 N.W.2d at 386 (noting “parties seeking

discovery should normally be justified in believing they have received

substantially all the information requested”).

      As rule 1.508(3) provides, the district court may order sanctions

for violations. See Whitley, 816 N.W.2d at 388. This decision “rests with
the sound discretion of the trial court,” id., and “[w]e have been slow to

find an abuse of discretion,” Sullivan v. Chi. & Nw. Transp. Co., 326

N.W.2d 320, 324 (1982) (finding no abuse of discretion in trial court’s

exclusion of testimony based on discovery violation); see also, e.g.,

Whitley, 816 N.W.2d at 388–89 (affirming district court’s decision to

grant a continuance rather than exclude evidence); Lawson, 792 N.W.2d

at 260 (affirming district court’s limitation of evidence based on late

supplementation     that   “came   days    before   trial   and   after   one

continuance”).    In reviewing a district court’s ruling in a discovery

matter, we remain mindful that

      [a] trial should be a search for the truth, and our rules of
      discovery are an avenue to achieving that goal.         The
      discovery process seeks to make a trial into a fair contest
      with the basic issues and facts disclosed to the fullest
      practicable extent.

Whitley, 816 N.W.2d at 386 (internal quotation marks omitted).

      We must determine whether the district court appropriately

considered the available options.     In Whitley, we reiterated that the

district court should consider the following factors:

      “1. the parties’ reasons for not providing the challenged
      evidence during discovery;
                                          17
       2. the importance of the evidence;
       3. the time needed for the other side to prepare to meet the
       evidence; and
       4. the propriety of granting a continuance.”

Id. at 388 (quoting Lawson, 792 N.W.2d at 259). “While the sanction for

the failure to supplement discovery can include exclusion of the evidence

at trial, the trial court can also deny a request to exclude evidence.” Id.

Exclusion of an expert is an extreme sanction and “is justified only when

prejudice would [otherwise] result.” Lambert v. Sisters of Mercy Health

Corp., 369 N.W.2d 417, 422 (Iowa 1985) (internal quotation marks

omitted).

       Schmidt informed the Hagenows of Dr. Bekavac’s revised opinion

sixty-seven days before trial, well before the requirement in rule 1.508(3)

to supplement responses at least thirty days before trial.5 The Hagenows

do not claim that Schmidt knew of Dr. Bekavac’s revised opinion earlier

and thereby failed to disclose it “as soon as practicable” under that rule.

       Significantly, the Hagenows have not shown they were prejudiced

by the disclosure of Dr. Bekavac’s revised opinion just over two months

before trial. The Hagenows were able to retain a rebuttal expert ten days

later, with trial still seven weeks away. The parties deposed both experts
before trial.      The district court offered the Hagenows’ counsel a

continuance, which he declined. We hold the district court acted within


       5Plaintiffs’ experienced trial counsel was on notice since Schmidt’s answer filed

on February 9, 2011, that defendant claimed a sudden medical emergency caused the
accident. Discovery responses, served April 6, stated defense counsel may call treating
physicians to give opinion testimony at trial, including Dr. Bekavac. The records of
Schmidt’s rehabilitation physician, Dr. Malicka-Rozek, indicated the stroke preceded
and caused the accident. Her records were produced to the Hagenows’ counsel by
autumn 2011. Schmidt’s formal designation of Dr. Bekavac as a testifying expert on
November 29 reserved her right to elicit opinion testimony at trial from other treating
physicians. For these reasons, disclosure of Dr. Bekavac’s causation opinion on
February 24, 2012, may not have been a complete surprise to the Hagenows.
                                    18

its discretion by allowing Dr. Bekavac’s expert opinion testimony.      We

therefore affirm the rulings denying Hagenows’ motions to exclude

Dr. Bekavac’s testimony at trial.    Accordingly, his testimony may be

considered in deciding the next issue—whether the evidence was

sufficient to submit a defense based on legal excuse or sudden

emergency.

    IV. Whether the District Court Committed Reversible Error in
Submitting the Sudden Emergency Instruction.

      The Hagenows had the burden to prove Schmidt’s negligence.

Crashing into a pickup truck stopped at a red light ordinarily would

constitute negligence per se. But, what if the reason Schmidt failed to

see the Hagenows’ vehicle stopped in front of her is that her unforeseen

stroke caused a sudden loss of vision?      How did she fail to exercise

reasonable care if she was unaware of her loss of vision before the crash?

We must determine whether the district court committed reversible error

in instructing the jury on Schmidt’s sudden medical emergency under

these circumstances. We review the evidence in the light most favorable

to Schmidt as the party asserting the defense. See Weiss, 501 N.W.2d at

481. We begin our analysis with a look at the law of legal excuse and

sudden emergency.
      “The doctrine of legal excuse permits the jury to excuse a

defendant’s failure to obey statutory law when confronted with an

emergency not of his or her own making.” Id. at 480. We have identified

four categories of legal excuse:

      (1) anything that would make it impossible to comply with
      the statute or ordinance;
      (2) anything over which the driver has no control which
      places the driver’s motor vehicle in a position contrary to the
      provisions of the statute or ordinance;
                                          19
       (3) where the driver of the motor vehicle is confronted by an
       emergency not of the driver’s own making, and by reason of
       such an emergency, the driver fails to obey the statute; and

       (4) where a statute specifically provides an excuse or
       exception.

Rowling v. Sims, 732 N.W.2d 882, 885 (Iowa 2007) (internal quotation

marks omitted).       “A jury should only be instructed on the category of

legal excuse supported by the evidence.” Id.6

       “Unlike the doctrine of legal excuse—which exonerates a party

from liability for negligence per se—the sudden emergency doctrine is

merely an expression of the reasonably prudent person standard of

care.”7 Weiss, 501 N.W.2d at 481. “It expresses the notion that the law

       6On   appeal, the Hagenows argue the sudden emergency instruction was
inappropriate because “[i]t is impossible for [Schmidt] to offer competent medical
evidence that her knowledge of pre-existing medical conditions did not impair her
ability to drive with due care.” In a conclusory fashion, they list ailments from
Schmidt’s medical history, including headaches and sleep apnea, to allege she
“contributed to the creation of the emergency.” The Hagenows did not make this
specific objection to the sudden emergency instruction at trial, and in any event, it
lacks merit. Schmidt’s own testimony refutes the Hagenows’ argument, showing she
was able to drive without incident up until the time of her stroke. We conclude her
medical history did not rise to a level that, as a matter of law, she should have
anticipated her stroke and refrained from driving. Her defense was for the jury. This is
not a case in which a driver was beginning to experience symptoms and could have
pulled over before the accident, nor is it a case in which a medical emergency resulted
from the driver’s careless failure to take medications.
       7In  Weiss, we declined the opportunity to abandon the sudden emergency
instruction, despite our recognition “that the doctrine of sudden emergency has come
under increasing attack in recent years.” 501 N.W.2d at 480. We did so after an
analysis of conflicting authorities led us to the conclusion that “a jury may be aided by
a succinct and narrowly drafted instruction that tells it the actor is held only to the
standard of reasonable care under the circumstances posed by the emergency.” Id. at
481.
        The Colorado Supreme Court is the latest to abolish the sudden emergency
doctrine. Bedor v. Johnson, 292 P.3d 924, 927–31 (Colo. 2013) (collecting cases). Two
dissenting justices favored retaining the sudden emergency defense. Justice Boatwright
relied on stare decisis:
               The majority abolishes the sudden emergency instruction in
       Colorado negligence law because it states that this legal principle’s
       potential to mislead the jury greatly outweighs its minimal utility. Our
       earlier precedent rejected this view because we determined this doctrine
                                           20

requires no more from an actor than is reasonable to expect in the event

of an emergency.” Id. We have repeatedly defined “sudden emergency”

as

       “(1) an unforeseen combination of circumstances which calls
       for immediate action; (2) a perplexing contingency or
       complication of circumstances; [or] (3) a sudden or
       unexpected occasion for action, exigency, pressing
       necessity.”

Vasconez v. Mills, 651 N.W.2d 48, 54 (Iowa 2002) (quoting Foster v.

Ankrum, 636 N.W.2d 104, 106 (Iowa 2001)).

       In the case before us, Instruction No. 19 defined “sudden

emergency” as “an unforeseen combination of circumstances that calls

for immediate action or a sudden or unexpected occasion for action.” It

also reflected a reasonable person standard, stating:

       A driver of a vehicle who, through no fault of her own, is
       placed in a sudden emergency, is not chargeable with
       negligence if the driver exercises that degree of care which a
       reasonably careful person would have exercised under the
       same or similar circumstances.

       We have held a sudden emergency instruction is inappropriate if

the “emergency” is of the type that a reasonably prudent person should

be prepared for or if the circumstances allowed a defendant time to
assess the situation.         See id. at 54–55 (holding sudden emergency

instruction was inappropriate when driver failed to see biker riding on

the side of the road); Foster, 636 N.W.2d at 107 (rejecting sudden
______________________
       was helpful to the jury. Nothing has changed since we reached this
       conclusion and stare decisis dictates that we continue to give effect to
       our earlier pronouncements.
Id. at 932 (Boatwright, J., dissenting); see also Moran v. Atha Trucking, Inc., 540 S.E.2d
903, 913 (W. Va. 1997) (retaining sudden emergency defense with comparative fault
system after thorough review of criticism and conflicting authorities in other
jurisdictions). No party in this case has asked us to abandon the sudden emergency
doctrine.
                                    21

emergency instruction when defendant had ten to fifteen seconds to

deliberate); Weiss, 501 N.W.2d at 482 (denying instruction when “[t]he

facts reveal no more than the everyday hazard of driving through a

school parking lot and the not uncommon appearance of pedestrians

crossing the traveled way to reach their parked cars”).        Whether a

sudden emergency occurred is typically a fact question entrusted to the

jury.   See Weiss, 501 N.W.2d at 481.       The burden is on the party

asserting the defense. Blair, 387 N.W.2d at 352. “[I]f there is substantial

evidence that an emergency had developed, the jury should be instructed
thereon.” Bangs v. Keifer, 174 N.W.2d 372, 374 (Iowa 1970).

        A. The Evidence Was Sufficient to Submit a Defense Based on

Sudden Emergency or Legal Excuse. The Hagenows argue a sudden

emergency instruction was inappropriate because the evidence was

insufficient to prove that Schmidt suffered a stroke prior to the accident

or that her stroke caused the accident. They assert Schmidt’s testimony

that she was able to see the red light as she approached the intersection

and that she did not lose consciousness proves she did not suffer her

stroke before the accident. They argue “there simply is no competent

medical evidence to support such a finding despite [Dr. Bekavac’s

testimony]” and describe Schmidt’s evidence as “speculative at best.”

The Hagenows point to the fact that Schmidt did not report her vision

loss until over an hour after arriving at the hospital as evidence the

stroke occurred after the accident.       They also contend that, even

assuming Schmidt’s stroke occurred prior to the accident, this would not

establish a sudden emergency defense because her vision loss occurred

only in the left half of both of her eyes and would not have prevented her
from viewing the Hagenows’ vehicle directly in front of her.
                                        22

      We disagree.     The Hagenows’ insufficiency argument collapses

upon our determination that Dr. Bekavac’s testimony was properly

admitted.       Reviewing   all   the   evidence—including   Dr.   Bekavac’s

testimony—in the light most favorable to Schmidt and “taking into

consideration all reasonable inferences that could be fairly made by the

jury,” Kiesau v. Bantz, 686 N.W.2d 164, 171 (Iowa 2004), we hold the

evidentiary record supports submission of a legal-excuse defense based

on Schmidt’s sudden medical emergency.

      Drs. Friedgood and Bekavac agreed Schmidt suffered a stroke on
the afternoon of November 10, 2008, that caused permanent loss of the

left half of her vision in both eyes.        Though Dr. Bekavac conceded he

could not definitively determine when the stroke occurred, medical

evidence supported his opinion that the stroke most likely preceded the

accident.   Dr. Bekavac explained there was no evidence that Schmidt

suffered head trauma during the accident that would have precipitated

the stroke. Dr. Bekavac found it significant that Schmidt did not report

losing consciousness before or after the accident, but rather reported

confusion. Dr. Friedgood confirmed that “[c]onfusion can be a symptom

of a stroke.”

      Both experts testified Schmidt could have lost half of her vision

before the accident and yet failed to notice it until later at the hospital.

Dr. Bekavac noted that a stroke happens quickly and often painlessly,

and he was unsurprised Schmidt failed to realize she had suffered one.

Dr. Friedgood agreed that when a person loses only half of his or her

normal field of vision, that person could initially be unaware of the loss.

This is because the left half of a person’s vision does not “go black” upon
suffering a stroke. Rather, a person would simply be unable to perceive

the left half of his or her range of vision, in the same way that people are
                                     23

unable to perceive what is behind them but do not “see” blackness.

Dr. Friedgood commented, “Eventually they become aware of it reflexively

and then they deal with it, but initially they may not be aware, and that’s

why they bump into things and get into trouble.”

      Finally, because of the nature of her vision loss, it was possible

Schmidt could have observed the red light and yet failed to perceive the

Hagenows’ vehicle. Both experts discussed how the loss of vision in the

left half of both of her eyes would have negatively affected Schmidt’s

ability to drive.   Dr. Friedgood noted that Schmidt’s ability to perceive
objects in front of her would depend upon how she moved her head and

eyes: if her eyes or head turned to the right, she would be unable to see

objects directly in front of her because they would be on the left side of

her field of vision. As Dr. Bekavac testified, if Schmidt looked to her right

in preparation of a right turn at the intersection, everything straight

ahead of her, now in the left part of her visual field, would have

disappeared.

      Based on this evidence, a reasonable juror could find that Schmidt

rear-ended the Hagenows’ vehicle because of her stroke and loss of

vision. We conclude the evidence was sufficient to submit the defense.

      B. Any Error in the Wording of the Sudden Emergency

Instruction Was Harmless.       The Hagenows next argue the wording of

the sudden emergency instruction did not fit the facts. Instruction 19

required the jury to find the emergency was an “unforeseen combination

of circumstances that calls for immediate action or a sudden or

unexpected occasion for action.” Schmidt, however, was unaware of her

vision loss and thus had no sudden choice or action to take. The court
of appeals reversed on that basis.        Our court has never squarely
                                     24

addressed the applicability of the sudden emergency defense under these

circumstances.

       In Weiss, we listed “a sudden heart attack” as an example of a

situation that could warrant a sudden emergency instruction.             501

N.W.2d at 482; see also Fitas v. Estate of Baldridge, 657 N.E.2d 323,

326–27 (Ohio Ct. App. 1995) (finding heart attack suffered by driver of

automobile created sudden emergency that precluded liability of driver or

his wife); Diaz v. Sopade, 893 N.Y.S.2d 164, 165 (App. Div. 2010)

(concluding sudden emergency defense applied to motorist who, after
being assaulted by his passenger and rendered unconscious, struck a

bicyclist).   Quoting section 13 of the American Jurisprudence Proof of

Facts Third, our court of appeals in this case concluded a sudden

emergency instruction is intended only for circumstances in which a

defendant “has acted in response to a perceived peril and has made a

choice which in hindsight may be regarded as unwise or ill-considered,

but which was not unreasonable or imprudent under the stress of

surrounding circumstances.” 8 Am. Jur. Proof of Facts 3d § 13, at 424

(1990 & Supp. 2013) (emphasis added); see also Bardwell v. McLaughlin,

520 S.W.2d 277, 278–79 (Ark. 1975) (holding sudden emergency

instruction inappropriate when “it was physically impossible for appellee

to make a decisional act”); Hancock-Underwood v. Knight, 670 S.E.2d

720, 726 (Va. 2009) (holding driver who suffered acute medical crisis and

lost consciousness was not entitled to sudden emergency instruction

because “[t]here was no action he could take or did take”). Under this

view, “[w]here the actor has not made a decisional act in response to

peril, either because he was unaware of the peril, or where he perceived
the peril but did not have time to react to it, the doctrine logically has no

application.” 8 Am. Jur. Proof of Facts 3d § 13, at 424.
                                             25

       The Restatement (Third) of Torts: Liability for Physical and

Emotional Harm includes a separate section for disability—which does

not require advanced awareness or a rapid response.                            We have not

previously considered adopting the provisions of the Restatement (Third)

relevant to a sudden medical emergency.                     Section 11(b) on sudden

incapacitation best fits the facts of this case.8 Cf. Weiss, 501 N.W.2d at



       8Section   11(b) of the Restatement, entitled “Disability,” provides:
       The conduct of an actor during a period of sudden incapacitation or loss
       of consciousness resulting from physical illness is negligent only if the
       sudden incapacitation or loss of consciousness was reasonably
       foreseeable to the actor.
Restatement (Third) of Torts: Liab. for Physical & Emotional Harm § 11(b), at 130
(2005). Comment d to section 11 explains, “[s]udden incapacitation can be caused by a
heart attack, a stroke, an epileptic seizure, diabetes, or other medical conditions.” Id.
§ 11 cmt. d, at 131 (emphasis added). Significantly, section 11(b) does not require the
driver’s contemporaneous awareness of his medical emergency, nor a rapid decision or
action to be taken, as that would be impossible for a person who is unconscious or
incapacitated. Comment d elaborates:
       A typical case is sudden incapacitation that causes a driver to lose
       control of the car. This is distinctly dangerous and substandard driving
       which, absent the incapacitation, would easily merit a finding of
       negligence. Even so, when the incapacitation is itself unforeseeable, it
       follows that no reasonable precautions were available to the driver that
       could have avoided the risk of harm.
Id. Relatedly, section 15 of the Restatement (Third), entitled “Excused Violations,”
states that a statutory violation is excused if “the violation is reasonable in light of the
actor’s childhood, physical disability, or physical incapacitation.” Id. § 15(a), at 168.
        Unlike section 11(b), the Restatement’s “emergency” provision, section 9,
requires a rapid response. This provision provides: “If an actor is confronted with an
unexpected emergency requiring rapid response, this is a circumstance to be taken into
account in determining whether the actor’s resulting conduct is that of the reasonably
careful person.” Id. § 9, at 111. The Restatement (Third) defines “emergency” as
       the kind of event that prevents reasonable persons from exercising the
       kind of good judgment that such persons ordinarily exercise. An
       emergency is an event that requires a decision within an extremely short
       duration and that is sufficiently unusual so that the actor cannot draw
       on a ready body of personal experience or general community knowledge
       as to which choice of conduct is best.
Id. § 9 cmt. b, at 112.
                                    26

482 (recognizing “a sudden heart attack” may support a sudden

emergency defense).    The evidence supported a finding that Schmidt

suffered a stroke that caused her to lose vision, resulting in the rear-end

collision when she failed to see the Hagenow vehicle.         She had no

forewarning of the stroke. But, neither the parties nor the district court

raised the provisions of the Restatement (Third) when instructing the

jury in this case. We defer for another day our consideration of these

provisions of the Restatement (Third) because we hold the submission of

the instruction did not prejudice the Hagenows, and we affirm the
judgment for Schmidt without a retrial. Cf. Thompson v. Kaczinski, 774

N.W.2d 829, 839–40 (2009) (reversing summary judgment for defendant

and remanding for trial under scope of liability provisions of the

Restatement (Third) adopted in that opinion).

      Any error in the wording of the sudden emergency instruction

given was harmless.      See Koenig, 766 N.W.2d at 637 (noting only

prejudicial error requires reversal). The alleged erroneous wording in the

instruction made it more difficult for Schmidt to prove her sudden

emergency defense. That wording defined emergency as an “unforeseen

combination of circumstances that calls for immediate action or a

sudden or unexpected occasion for action.”         The Hagenows thereby

benefited from any error in the wording of the sudden emergency

instruction, such that the alleged error was nonprejudicial to them. See

Wells v. Enter. Rent-A-Car Midwest, 690 N.W.2d 33, 38 (Iowa 2004)

(holding a challenged special interrogatory “treated [appellants] more

favorably than the facts warranted [and,] [c]onsequently, there was no

prejudice in submitting [the special interrogatory] to the jury”); Sheets v.
Ritt, Ritt & Ritt, Inc., 581 N.W.2d 602, 607 (Iowa 1998) (holding

instructional error was harmless because “[appellant] is unable to show
                                    27

how her chance of recovery would have actually improved under the

instructions she requested”).

      In order to return a defense verdict in this rear-end collision case,

the jury must have found that Schmidt’s stroke caused the accident. As

the court of appeals and district court concluded, Schmidt was entitled

under the evidence to an instruction on legal excuse. The Hagenows fail

to show the alleged instructional error was prejudicial because they offer

no reason that omission of the challenged wording would have led to a

different verdict. See Sheets, 581 N.W.2d at 607 (rejecting challenge to
jury instructions when appellant was “unable to establish that the jury

might have reacted differently under her proposed instructions”). “Given

the clear focus of the experts’ disagreement, we do not see how the jury

could have been misled by the court’s instruction.” Estate of Hagedorn

ex rel. Hagedorn v. Peterson, 690 N.W.2d 84, 90 (Iowa 2004).

Accordingly, we conclude the district court correctly denied the

Hagenows’ motion for new trial.

      V. Disposition.

      For the foregoing reasons, we vacate the decision of the court of

appeals and affirm the district court’s judgment in favor of Schmidt.

      DECISION OF COURT OF APPEALS VACATED; DISTRICT

COURT JUDGMENT AFFIRMED.
