OPINION
ANDERSON, PAUL H„ Justice.In the case before us, we must determine whether using CIVJIG 91.40 to instruct a jury on aggravation of a preexisting injury or condition improperly shifts to the defendant the burden of apportioning a plaintiffs automobile accident injuries and her preexisting injuries. The subject of this action is an automobile accident that occurred when a vehicle driven by Mohamed Munye rear-ended Cheryl Rowe’s vehicle. Claiming that she suffered injuries from this accident, Rowe sued Munye for negligence. At trial, Rowe requested CIVJIG 91.40 to instruct the jury on aggravation because she claims her injuries from the accident aggravated injuries that preexisted the accident. Munye objected, contending that CIVJIG 91.40 misstates Minnesota law and impermissibly shifts the burden of proof from Rowe to him. The Hennepin County District Court granted Rowe’s request and included CIVJIG 91.40 in its instructions to the jury. The jury then awarded Rowe damages for medical expenses, pain, disability, and emotional distress. Munye moved for *733a new trial, arguing that CIVJIG 91.40 was an improper and prejudicial instruction. The court denied Munye’s motion and he appealed. The Minnesota Court of Appeals reversed and remanded for a new trial on damages. Rowe v. Munye, 674 N.W.2d 761 (Minn.App.2004). We affirm the court of appeals.
On November 21, 1999, as appellant Cheryl Rowe was making a left turn, respondent Mohamed Munye hit her vehicle from behind with his car. Munye initially claimed that he hit Rowe only because an unidentified vehicle pushed him into Rowe’s car. Rowe claimed that she suffered neck and shoulder injuries from this accident and sued Munye for negligence. Because Munye asserted that the unidentified vehicle caused the accident, Rowe also initially sued her insurance company, Employers Mutual Insurance Company/Dakota Fire Insurance Company, under the unidentified/uninsured driver terms of her policy. The district court subsequently dismissed Munye’s defense with prejudice when Munye repeatedly failed to cooperate with court instructions and discovery orders. Munye eventually conceded that he “bore complete and undisputed liability” for the accident. Thus, the only issue left for the jury to decide was the issue of damages.
At trial, Rowe testified about the accident and her resulting injuries. She testified that immediately after the accident, she had a headache and a sore neck, which continued to worsen. Rowe also claimed that as a result of the accident she developed a persistent numbness in her arm and hand. She testified that chiropractic treatment from Dr. Kelly Sheehan has provided some relief from her symptoms. An MRI scan taken in April 2000 showed a herniated disc in her neck. In June 2000, neurologist Dr. Ronald Tarrel examined Rowe and told her that surgery was not necessary, but that she could continue the chiropractic treatments. Rowe continued treatments with Dr. Sheehan about once a month.
Dr. Sheehan testified that he believes Rowe suffers from permanent injuries to her neck and upper back because of the accident and will need continuing supportive care at an annual cost of approximately $1,950. He testified that while some of Rowe’s x-rays show a preexisting degenerative joint disease, her back problems before the accident would not have been permanent. He did testify, however, that Rowe would have probably needed continued “maintenance” care based on her pre-accident injuries. Dr. Sheehan concluded that Rowe’s injuries were both caused by and aggravated by the accident with Mu-nye.
Neurologist Dr. Irman Altafullah, who independently examined Rowe on February 19, 2002, testified for Munye. Dr. Altafullah stated that he believes the accident did not cause Rowe to suffer from either a permanent injury or a permanent aggravation of a preexisting injury and that her degenerative back changes had developed over a long period of time. He did say, however, that he believes that the accident might have caused Rowe to suffer temporary aggravating injuries. He based his opinion on the nature of the accident, Rowe’s symptoms and improvement over time, and his examination, which, he said, did not reveal any objective findings of permanent injury.
Rowe’s preexisting injuries involved back, shoulder, and neck pain and headaches. For about 20 years before the accident with Munye, Rowe had periodically received chiropractic care for chronic neck and back discomfort. Her most recent visit to Dr. Sheehan was just a few days before the accident. In 1975, Rowe had been in a car accident, in which she *734was thrown against the windshield and broke two of her teeth. She also fell off a motorcycle in 1965. Rowe stated, however, that she suffered no lingering injuries from either of those earlier accidents. Despite her previous medical treatment for her back and neck, she testified that for a couple of weeks before the accident with Munye occurred, she had “felt really great” and “better than [she] had in a long time.”
Rowe also testified that her injuries from the accident with Munye have caused her to limit her involvement in activities and that she believes her life is more limited than it was before the accident. She claimed that, since the accident, she tires more quickly and has had to significantly curtail her volunteer work. Munye tried to show that Rowe’s injuries did not limit her activities and he attempted to prove that Rowe’s injuries were not severe because the impact from the accident was only a jolt and it did not cause her to hit anything inside her ear. Rowe requested $79,000 in damages: $6,000 for past medical expenses; $15,000 for past pain, disability, and emotional distress; $52,000 for future pain, disability, and emotional distress; and $6,000 for future medical expenses.
Rowe requested CIVJIG 91.40 because she claimed that the accident aggravated her previous back and neck problems. 4A Minn. Dist. Judges Ass’n, Minnesota Practice, Jury Instruction Guides — Civil, CIVJIG 91.40 (4th ed. 1999 & Supp. 2005).1 She did not claim that her aggravated injuries were not apportionable from her preexisting injuries. Munye did not submit any proposed jury instructions, but just before jury deliberations, he objected to Rowe’s request for CIVJIG 91.40, stating that he believed the instruction misstates Minnesota law. Munye argued that the instruction’s third sentence impermis-sibly shifts the burden of proving Rowe’s injuries to him. Instead of CIVJIG 91.40, Munye requested that the court give the now replaced 1986 CIVJIG 163 to the jury because the former instruction did not im-permissibly shift the burden of proof to the defendant. 4 Minn. Dist. Judges Ass’n, Minnesota Practice, Jury Instruction Guides — Civil, CIVJIG 163 (3d ed.1986). CIVJIG 163 was the jury instruction on aggravation from the Third Edition of the civil jury instruction guide and was replaced by CIVJIG 91.40 in the Fourth Edition.
The district court granted Rowe’s request and instructed the jury using the exact language of CIVJIG 91.40, only adding Rowe’s and Munye’s names. The court’s instructions on aggravation read as follows:
There is evidence that Cheryl Rowe had a pre-existing disability or medical condition at the time of the accident. Mohamed Munye is liable only for any damages that you find to be directly caused by the accident.
If you cannot separate damages caused by the pre-existing disability or medical condition from those caused by the accident, then Mohamed Munye is liable for all of the damages.
*735The jury found that Rowe had sustained a permanent injury and a 60-day disability as a result of the accident, but not medical expenses in excess of $4,000. It awarded her $24,500: $7,500 for past pain, disability, and emotional distress; $13,000 for future pain, disability, and emotional distress; and $4,000 for future health care costs and expenses. On November 14, 2002, the district court entered judgment for Rowe.
Munye moved for a new trial, claiming that the district court erred when it gave CIVJIG 91.40 because the instruction caused him prejudice. He objected to CIVJIG 91.40, arguing that it (1) misstates Minnesota law pursuant to a court of appeals decision, Blatz v. Allina Health Sys., 622 N.W.2d 376 (Minn.App.2001), rev. denied (Minn. May 16, 2001); and (2) unfairly prejudices his right to a fair trial by impermissibly shifting to him the burden of proving apportionment of damages. The court denied Munye’s motions and he appealed.
The court of appeals reversed the district court, concluding that CIVJIG 91.40 “impermissibly imposes on an at-fault defendant the burden of proving that he did not cause the portion of plaintiffs damages attributable to a pre-existing disability or condition.” Rowe, 674 N.W.2d at 767-68. The court went on to conclude that it could not determine whether the erroneous instruction influenced the jury in the award of damages. Id. at 770. Therefore, the court of appeals remanded for a new trial, but limited the scope of the trial to a determination of the amount of damages that Rowe sustained from the accident over and above the damages that normally would have followed from her preexisting condition. Id.
Rowe appeals to our court, contending that CIVJIG 91.40 is appropriate because it clearly and accurately states Minnesota law and ensures consistent jury instructions. Alternatively, she contends that CIVJIG 91.40 did not prejudice Munye because the jury appropriately separated the preexisting injury from the aggravation of that injury. Munye requests that we affirm the court of appeals’ decision to grant him a new trial on damages. He also requests that we conclude that CIVJIG 91.40 constitutes prejudicial error when given to the jury in a case with one liable defendant and a plaintiff who asserts aggravation of a preexisting injury.
I.
We review a district court’s decision on jury instructions under an abuse of discretion standard. Hilligoss v. Cargill, Inc., 649 N.W.2d 142, 147 (Minn.2002). District courts generally have “considerable latitude” in choosing jury instructions. Morlock v. St. Paul Guardian Ins. Co., 650 N.W.2d 154, 159 (Minn.2002). But a court errs if it gives a jury instruction that materially misstates the law. State v. Kuhnau, 622 N.W.2d 552, 556 (Minn.2001).
We begin our analysis with a brief summary of our case law on the burden of proof and aggravation of preexisting injuries. In a negligence action, the plaintiff generally has the burden of proving, by a preponderance of the evidence, damages caused by the defendant. Canada by Landy v. McCarthy, 567 N.W.2d 496, 507 (Minn.1997); see also 4A Minn. Dist. Judges Ass’n, Minnesota Practice, Jury Instruction Guides — Civil, CIVJIG 90.15 (4th ed. 1999) (“A party asking for damages must prove the nature, extent, duration, and consequences of his or her (injury) (harm).”). The plaintiff must demonstrate with reasonable certainty the nature and probable duration of the injuries sustained. Canada by Landy, 567 N.W.2d at 507.
*736When an accident involves aggravation of preexisting injuries, we have required the defendant to pay only for the damages he or she caused over and above the consequences that would have occurred from the preexisting injury if the accident had not occurred. See, e.g., Nelson v. Twin City Motor Bus Co., 239 Minn. 276, 280, 58 N.W.2d 561, 563 (1953). In Schore v. Mueller, we said:
Our rule is that a person who has a preexisting disability is entitled to recover damages for an aggravation of that condition even though the particular consequences would not have followed absent his prior disability, recovery being limited, however, to the additional injury over and above the consequences which normally would have followed from the preexisting condition absent defendant’s negligence.
290 Minn. 186, 189, 186 N.W.2d 699, 701 (1971).
In aggravation cases, we have also indicated that the burden of proof remains on the plaintiff because aggravation is not an affirmative defense which shifts the burden to the defendant. See Leubner v. Sterner, 493 N.W.2d 119, 122 (Minn.1992). We have said, “ ‘[ajggravation of a preexisting physical condition’ is a measure of damages, not a theory of liability, even if one puts the word ‘negligent’ in front of the phrase.” Id. Thus, our case law is clear that the burden remains on the plaintiff in cases involving aggravation of a preexisting injury.
A limited situation where we have shifted the burden to the defendant involves the single indivisible injury rule set forth in Mathews v. Mills, 288 Minn. 16, 178 N.W.2d 841 (1970). In Mathews, we said that multiple defendants are jointly and severally liable when they, through independent consecutive acts of negligence closely related in time, cause indivisible injuries to the plaintiff. Id. at 20-21, 178 N.W.2d at 844. In Mathews, the plaintiff was injured in a highway chain collision involving multiple defendants. Id. at 18-19, 178 N.W.2d at 842-43. We held that where the tortious conduct of two or more actors has combined to bring about harm to the plaintiff, and one or more of the defendants seeks to limit his or her liability by claiming that the harm is capable of apportionment, the burden of proving the apportionment is on the defendant(s). Id. at 22, 178 N.W.2d at 845. We recently applied Mathews in Canada by Landy, where we placed the burden of proving apportionment on a jointly and severally liable landlord who caused lead poisoning injuries to a child. Canada by Landy, 567 N.W.2d at 507-08. Our holdings in Mathews and Canada by Landy are consistent with the Restatement (Second) of Torts, which only shifts the burden of proof to the defendant in situations that involve the combined tortious conduct of two or more actors who are seeking to limit their liability for the harm they have caused the plaintiff.2 Restatement (Second) of Torts *737§ 433 B (1965); see also Morlock, 650 N.W.2d at 165.
It is within this contextual framework that we need to examine CIVJIG 91.40. CIVJIG 91.40 is designed to be given in cases involving aggravation of preexisting injuries. It reads:
There is evidence that (plaintiff) had a pre-existing disability or medical condition at the time of the accident. (Defendant) is liable only for any damages that you find to be directly caused by the accident.
[If you cannot separate damages caused by the pre-existing disability or medical condition from those caused by the accident, then (defendant) is liable for all of the damages.]
CIVJIG 91.40 (emphasis added). The parties disagree on whether the instruction’s third sentence misstates Minnesota law because it shifts the burden of separating damages to the defendant. The third sentence instructs the jury to find the defendant liable for all damages when the jury is unable to apportion the plaintiffs injuries between the injuries caused by the defendant and the plaintiffs preexisting injuries.
Because Munye believes the third sentence of CTVJIG 91.40 misstates Minnesota law, he requested that the district court instruct the jury using the Third Edition’s instruction on aggravation, CIVJIG 163, which reads:
A person who has a defect or disability at the time of an accident is nevertheless entitled to damages for any aggravation of such pre-existing condition, even though the particular results would not have followed if the injured person had not been subject to such pre-existing condition. Damages are limited, however, to those results which are over and above those which normally followed from the pre-existing condition, had there been no accident.
4 Minn. Dist. Judges Ass’n, Minnesota Practice, Jury Instruction Guides — Civil, CIVJIG 163 (3d ed.1986). We have previously cited CIVJIG 163 as a proper statement of Minnesota law. Leubner, 493 N.W.2d at 122. CIVJIG 91.40 and CIVJIG 163 conflict to the extent that CIVJIG 91.40 places the burden to apportion the damages on the defendant. CIVJIG 163 does not provide any explicit default rule when the jury cannot apportion damages; thus, under CIVJIG 163, the burden of proof remains on the plaintiff.
We previously looked at CIVJIG 91.40 in Morlock, when we determined that the district court erred when it gave CIVJIG 91.40 to the jury because neither party’s theory of the case required the jury to distinguish between a preexisting condition and any aggravation caused by the defendant’s negligence. 650 N.W.2d at 161. The plaintiff had contended that a car accident caused all of his injuries and the defendant argued that the accident caused none of the plaintiffs ongoing injuries. Id. at 156-58. We therefore did not decide whether CIVJIG 91.40 misstated Minnesota law, but we suggested that “it may be possible that CIVJIG 91.40 could be inappropriate in a situation where a plaintiff is seeking both ‘new’ damages and damages for aggravation of an admitted to preexisting condition.” Id. at 161-62. In this case, Rowe’s theory is that she was injured in the November 1999 accident with Munye and that these injuries aggravated her preexisting back problems. Unlike Mor-lock, Rowe’s theory requires the jury to distinguish between new and preexisting injuries; therefore, we now must decide whether CIVJIG 91.40 is a correct statement of law.
*738Rowe argues that CIVJIG 91.40 is a better statement of law than CIVJIG 163 because “it ensures that parties support their theories and/or defenses.” She claims that CIVJIG 91.40 still requires the plaintiff to satisfy her burden of proof, but it “does not allow the defendant to simply muddy the issues and/or confuse the jury in hope of preventing a recovery.” Rowe asserts that the burden for the failure to prove damages should not fall on the innocent plaintiff, but rather on the at-fault defendant. She maintains that the underlying rationale of CIVJIG 91.40 should not be limited to cases where multiple tortfea-sors are jointly and severally liable; rather, the reasoning of Mathews and Canada by Landy should be extended to include the situation before us. In those two cases involving jointly and severally liable tort-feasors, we placed the burden on the defendant to prove apportionment of damages. Rowe asserts that the standard for the jury should be the same whether the accident involved jointly and severally liable tortfeasors or whether it involved a single tortfeasor and an innocent cause, such as a preexisting injury. She claims that there is no basis or justification for the different standards.
Munye, however, argues that CIVJIG 91.40 misstates Minnesota law because it erroneously combines joint and several liability rules with aggravation of preexisting injury rules and improperly shifts the burden of proving damages from the plaintiff (Rowe) to the defendant (Munye). He claims that Minnesota law requires that a plaintiff who asserts aggravation of a preexisting injury must prove that the defendant caused damage over and above the preexisting injury and that CIVJIG 91.40 “completely erases the plaintiffs burden of proof in aggravation cases by shifting that burden to the defendant.”
Munye also claims that Minnesota law has never shifted the burden of proof to the defendant in cases involving a single defendant who caused aggravation of a preexisting injury, as is the case here. He states that only one exception allows the burden of proof to be shifted from the plaintiff to the defendant. For this exception, Munye relies on the court of appeals decision in Blatz for two requirements: (1) joint and several tortfeasors, and (2) single indivisible damages. See 622 N.W.2d at 390. He contends that Blatz was correctly decided and asserts that the policy reason for this exception — that the plaintiff should not be prejudiced for failing to know the precise apportionment of damages caused by multiple tortfeasors — is not present in aggravated injury cases. Moreover, he claims that in an aggravated injury case, the plaintiff is in the best position to know the extent of the preexisting injuries and the degree of aggravation. We agree that our case law supports Munye’s position.
In cases where the jury cannot apportion the plaintiffs new injuries from the plaintiffs preexisting injuries, CIVJIG 91.40 shifts the burden of proving the extent of the new injuries to the defendant. Thus far, we have shifted the burden to the defendant only in cases involving multiple tortfeasors who were jointly and severally responsible for a single injury to the plaintiff. See Mathews, 288 Minn. at 21, 178 N.W.2d at 844; Canada by Landy, 567 N.W.2d at 507-08. The case before us today, however, does not trigger the single indivisible injury rule set forth in Mathews. Here, only one defendant is involved and the injuries were not closely related in time.
We do not agree with the assertion that CIVJIG 91.40 finds its basis for support in Canada by Landy, an application of the *739rule in Mathews.3 In Canada by Landy, a child had suffered repeated lead poisoning at multiple dwellings owned by different defendants. 567 N.W.2d at 499. The ap-pellani/defendant in Canada by Landy had been negligent in performing lead abatement cleanup. Id. at 508. We held that, when the district court determined that the child’s lead poisoning injuries could be divided between two different points in time, the defendant had the burden to prove that his acts did not cause the plaintiffs injuries. Id. at 507-08. In reaching our decision, we followed Mathews, and placed on the defendant, who was jointly and severally liable for the damages, the burden of proving that the plaintiffs injuries could be apportioned. Id. We further noted that, under “the facts of this case,” the defendant also had the burden of apportioning damages related to aggravation of the child’s preexisting injuries. Id. at 508. To the extent that Rowe reads Canada by Landy to place the burden of proof on the defendant in all cases involving aggravation of a preexisting injury, her reading is too broad. Thus, for us to conclude that CIVJIG 91.40 is an appropriate statement of the law in this case, we would need to extend the rationale of Mathews and Canada by Landy to all cases involving aggravation where the jury needs to apportion the plaintiffs injuries.
If we were to extend the law to follow Rowe’s arguments, Minnesota courts and juries would no longer need to distinguish between aggravation of a preexisting injury and the single indivisible injury rule with multiple tortfeasors. In each of these cases, the defendant would have the burden to prove that he or she had not caused all of the damages to the plaintiff. Essentially, we would “let the tie go to the plaintiff’ to ensure that the plaintiff is not undercompensated and we would treat a plaintiff with preexisting injuries the same as a plaintiff who is injured by jointly and severally liable tortfeasors.
But treating the plaintiffs the same in these situations ignores differences that become important when viewed in light of three policies woven through our case law: (1) the policy of protecting the innocent plaintiff over the tortfeasor, Mathews, 288 Minn, at 22, 178 N.W.2d at 845; (2) the policy of ensuring that the defendant is responsible only for the damages that he or she caused, Leubner, 493 N.W.2d at 122; and (3) the policy of placing the burden on the party with the greater amount of information, Morlock, 650 N.W.2d at 165; see also Mathews, 288 Minn. at 24, 178 N.W.2d at 846. Placing the burden on the defendant in all situations where the jury is unable to separate the damages would further the first policy, but would disregard the other two.
We conclude that extending the rationales of Mathews and Canada by Landy to aggravation cases that involve only one defendant could have the tendency to over*740compensate the plaintiff. A critical fact of both Mathews and Canada by Landy was that there were multiple defendants who were jointly and severally liable for 100% of the harm. Jointly and severally liable defendants already bear the risk of failure of proof because, if they are not able to prove that the damages can be apportioned, they are each liable for all of the damages. See Dan B. Dobbs, The Law of Torts § 170 at 412-14 (2000). The single defendant does not bear the same risk in an aggravation case, where the defendant is liable only for the damages that he or she caused. Schore, 290 Minn, at 189, 186 N.W.2d at 701.
Placing the burden of apportionment on the plaintiff when multiple defendants are jointly and severally liable would serve no purpose because in that situation, the defendants are jointly liable for 100% of the harm and are only trying to reduce their individual liability relative to other defendants. In a case of a single defendant and aggravation of a preexisting injury, however, the allocation must be between the defendant and the plaintiff. See Mayer v. N. Arundel Hosp. Ass’n, 145 Md.App. 285, 802 A.2d 483, 494 (2002). Because there is no presumption that the defendant caused 100% of the plaintiffs damage, shifting the burden to the defendant could force the defendant to pay for damages he did not cause. Thus, CIVJIG 91.40 is not the next logical step after Canada by Landy because different concepts are involved.4
Additionally, in a case involving aggravation of a preexisting injury, the plaintiff is likely to have more knowledge than the defendant of the extent of the preexisting injury. But, where there are multiple tortfeasors and injuries that are closely related in time, the plaintiff and the defendant will start at approximately the same point of knowledge. We conclude that, in the former circumstances, to require the defendant to separate the new injury from the preexisting injury improperly places the burden on the party with the lesser amount of information and again might have the tendency to overcompensate the plaintiff.
The dissent claims support for its argument that the burden of proof should be shifted to the defendant under CIVJIG 91.40 by using cases involving the eggshell plaintiff doctrine. See, e.g., Wolbers v. Finley Hosp., 673 N.W.2d 728 (Iowa 2003).5 But the eggshell plaintiff *741doctrine and CIVJIG 91.40, which shifts the burden to the defendant, involve distinguishable concepts.6 The eggshell plaintiff doctrine states that “[w]here a tort is committed, and injury may reasonably be anticipated, the wrongdoer is liable for the proximate results of that injury, although the consequences are more serious than they would have been, had the injured person been in perfect health.” Ross v. Great N. Ry. Co., 101 Minn. 122, 125, 111 N.W. 951, 953 (1907). The eggshell plaintiff doctrine is not a mechanism to shift the burden of proof to the defendant) rather, it makes the defendant responsible for all damages that the defendant legally caused even if the plaintiff was more susceptible to injury because of a preexisting condition or injury. Under this doctrine, the eggshell plaintiff still has to prove the nature and probable duration of the injuries sustained. Cf. Canada by Landy, 567 N.W.2d at 507. We note that other courts also recognize that the two concepts are different. Iowa recognizes the eggshell plaintiff doctrine, but does not shift the burden of proving apportionment to the single defendant in injury aggravation cases. See Waits v. United Fire & Cas. Co., 572 N.W.2d 565, 577 (Iowa 1997); Foggia v. Des Moines Bowl-O-Mat, Inc., 543 N.W.2d 889, 893-94 (Iowa 1996). Our decision today in no way changes our case law on the eggshell plaintiff doctrine.
We recognize that it is conceivable that a person could have both an injury that involves aggravation of a preexisting injury and an injury that was more severe because the plaintiff was more susceptible to injury.7 In fact, this was the case in Waits, where the Iowa Supreme Court held that a jury could receive instructions on both the eggshell plaintiff doctrine and on aggravation of a preexisting injury. 572 N.W.2d at 578. But, in recognizing the difference between the concepts, the Iowa court properly required that the jury be provided additional guidance on how to *742interpret both instructions. Id. Waits illustrates that the eggshell plaintiff doctrine and the burden-shifting mechanism of CIVJIG 91.40 should not be confused.
We agree that a defendant should be responsible for the harm that the defendant caused even if the harm is more severe because the plaintiff is more susceptible to injury — the eggshell plaintiff doctrine. But it does not follow, in a case involving aggravation of a preexisting injury, that a defendant should also pay for the preexisting injury. The defendant should pay for the aggravation, but not for the preexisting injury or condition. See Dobbs, supra, § 188 at 465. It is incorrect to assert that the defendant is “given a break” when the plaintiff is held to prove the extent and nature of her injuries. This is traditionally where we have placed the burden of proof under our tort law. Moreover, it would be improper to make the defendant responsible for proving any apportionment between the preexisting injury and the new injury when the plaintiff has superior knowledge of the preexisting injury.
We share the dissent’s concerns that the plaintiff not be undercom-pensated when a jury has difficulty separating the plaintiffs injuries caused by the defendant from her preexisting injuries, but we conclude that CIVJIG 91.40 is not the proper solution. CIVJIG 91.40 tries to do too much by casting a wider net than just those cases where apportionment is not possible. The third sentence of CIVJIG 91.40 attempts to address the situation when the jury “cannot separate damages caused by the pre-existing disability or medical condition from those caused by the accident” and is not intended to shift the burden to the defendant in every case. But, when confusing or eon-flicting testimony, jury indecision, or juror disagreement could lead to the jury’s inability to separate damages, we believe, rather than placing all uncertainty on the defendant, the better option is for the jury to make a rough apportionment so that the plaintiff receives fair compensation for her injuries. See Montalvo v. Lapez, 77 Hawaii 282, 884 P.2d 345, 363 (1994) (concluding that the jury should be instructed to roughly apportion between injuries a plaintiff received in separate accidents). We agree with the court of appeals that “it would be the exceptional case in which there is no reasonable basis for apportionment.” Rowe, 674 N.W.2d at 768; see also Dobbs, supra, § 174 at 425 (noting that surprising bases for apportionment can be found).
To sum up our analysis, we conclude that CIVJIG 91.40 creates confusion for the jury and blurs the distinctions among a plaintiff with an aggravation of a preexisting injury, a plaintiff injured by joint and several tortfeasors, and the eggshell plaintiff doctrine. Adoption of CIVJIG 91.40 would change our case law and would shift the burden of proving apportionment to the defendant in cases involving a single defendant and aggravation of a preexisting injury. We choose not to do so. The defendant should be responsible only for the injuries that are legally caused by the defendant’s negligence. CIVJIG 91.40 goes too far by making the defendant responsible for injuries that he did not cause. We therefore hold that the district court erred in giving CIVJIG 91.40 to the jury and that CIVJIG 91.40, as presently written, misstates Minnesota law on the defendant’s burden of proof in a case involving one defendant and aggravation of the plaintiffs preexisting injury or condition.8
*743II.
Our conclusion that the district court erroneously gave the jury an instruction that misstates the law does not end our analysis in this case. A complainant will not receive a new trial for errors in jury instructions unless the error was prejudicial. Lewis v. Equitable Life Assurance Soc’y of the U.S., 389 N.W.2d 876, 885 (Minn.1986). Therefore, we must determine whether Munye was prejudiced by the giving of this instruction. In determining whether erroneous instructions resulted in prejudice, we must construe the instructions as a whole from the standpoint of the total impact on the jury. Kroning v. State Farm Auto. Ins. Co., 567 N.W.2d 42, 48 (Minn.1997). We will, however, give the complainant the benefit of the doubt by granting the complainant a new trial if the effect of the erroneous instruction cannot be determined. See Morlock, 650 N.W.2d at 159.
Rowe argues that, if the district court erred in giving CIVJIG 91.40, the error was not prejudicial to Munye because (1) the jury’s finding of permanent injury to Rowe refutes the defendant’s argument that Rowe suffered no permanent injury; and (2) the jury did not have to rely on the last sentence of CIVJIG 91.40 because it “clearly apportioned the damages.” Rowe contends that, because the jury awarded her only a portion of the damage award she requested, the jury did “in fact separate the pre-existing from the aggravation injuries” and Munye suffered no prejudice.
Munye argues that CIVJIG 91.40 caused him substantial prejudice because this instruction misstated his burden of proof. He contends that any argument that the jury may have apportioned the damages between the new damages and those that existed before the accident “is purely speculative.” As a result, he asserts that because the total impact of CIVJIG 91.40 on the jury cannot be determined, he is entitled to a new trial.
We conclude that Munye has the stronger argument. Because the jury was not properly instructed on aggravation of injuries caused by the accident over Rowe’s preexisting injuries, we cannot determine how the jury decided the question of damages. Although Rowe did not explicitly argue that her new injuries were not ap-portionable from her preexisting injuries, because of the potential confusion created by CIVJIG 91.40, we cannot necessarily conclude that the jury did not rely on CIVJIG 91.40’s third sentence. The award could reflect that the jury did not apportion the damages, but found that Rowe’s claimed damages were excessive, or it could reflect that the jury did apportion Rowe’s injuries. The jury verdict does not specify which of these options is correct. We therefore hold that because we cannot determine the total effect of CIVJIG 91.40 based on the information before this court, Munye is entitled to a new trial on damages.
Affirmed.
BLATZ, C.J., took no part in the consideration or decision of this case.. The Jury Instmction Guides — Civil is a volume of civil jury instructions that have been discussed and reviewed by a group of approximately 20 trial judges and published under the guidance of the Minnesota District Judges’ Association. The First Edition was published in 1963, the Second in 1974, the Third in 1986, and the Fourth in 1999. The jury instruction guides have been created so that trial judges have an available resource, written in language understandable by lay juries, to instruct juries on the substantive law. The guide, however, explicitly states that it is only a guide and that judges should not rely on it as their exclusive source for substantive law.
. Restatement (Second) of Torts § 433 B (1965) provides:
(1) Except as stated in Subsections (2) and (3), the burden of proof that the tortious conduct of the defendant has caused the harm to the plaintiff is upon the plaintiff.
(2) Where the tortious conduct of two or more actors has combined to bring about harm to the plaintiff, and one or more of the actors seeks to limit his liability on the ground that the harm is capable of apportionment among them, the burden of proof as to the apportionment is upon each such actor.
(3)Where the conduct of two or more actors is tortious, and it is proved that harm has been caused to the plaintiff by only one of them, but there is uncertainty as to which one has caused it, the burden is upon each such actor to prove that he has not caused the harm.
. The use note to CIVJIG 91.40 no longer claims that the instruction has a basis in Canada by Landy. Although we declined to decide the correctness of CIVJIG 91.40 in Morlock, the Committee on Jury Instruction Guides subsequently modified CIVJIG 91.40 and rewrote the accompanying use note. See 4A Minnesota District Judges Association, Minnesota Practice, Jury Instruction Guides— Civil, CIVJIG 91.40 (4th ed. Supp.2005). It appears that the committee surrounded the last sentence of CIVJIG 91.40 with brackets to reflect the fact that we had not definitively decided the issue of burden of proof in cases where there is no basis for apportionment and because the court of appeals had determined that the third sentence of CIVJIG 91.40 misstates Minnesota law. See id. Previously, the use note stated that “the burden of apportioning damages appears to be with the defendant.” The basis cited for this earlier language was our decision in Canada by Landy, 567 N.W.2d at 496. See CIVJIG 91.40.
. It appears that the dissent misreads Restatement (Second) of Torts § 433 B(2), cmt. d, in stating that the Restatement shifts the burden or that the majority concedes any shifting of the burden to the defendant in single-defendant aggravation situations. Comment d provides the policy reason for shifting the burden to defendants when “two or more actors” are involved in the tortious conduct. See id.; see also Foggia v. Des Moines Bowl-O-Mat, Inc., 543 N.W.2d 889, 894 (Iowa 1996) (discussing the inapplicability of § 433 B to situations involving only one tortfeasor). Moreover, the dissent’s interpretation that § 433 B(2) applies to situations involving a single tortfeasor and aggravation of preexisting injuries would lead to odd results because, in order to fulfill the "two or more actors” requirement that is explicit in § 433 B(2), the burden of proof could be shifted to the defendant who caused the aggravation only where the preexisting injury was caused by a second tortfeasor. But not all preexisting injuries will have been caused by a second tortfeasor. The dissent's reading would therefore allow the defendant to be “given a break” in situations where the preexisting injury did not involve a second tortfeasor. Thus, the most logical and consistent reading of comment d is as an application of the Mathews single indivisible injury rule involving multiple defendants who are jointly and severally liable.
. Although there is support for the dissent’s position in case law from other jurisdictions, the dissent overstates that support. First, the dissent overstates the authority by saying that "Minnesota chooses a path rejected by every court but Iowa and Maryland.” Some states *741have not decided the issue; courts cannot reject what they have not decided. Second, the dissent has overstated the degree of support for its position in the cases it cites. For example, the Supreme Court of Hawaii determined that the jury should make a rough apportionment of damages and did not place all the responsibility on the defendant. See Montalvo v. Lapez, 77 Hawai'i 282, 884 P.2d 345, 363 (1994). Moreover, the Supreme Court of Alaska stated that it would only place the entire burden on the defendant upon a showing of "compelling injustice" to the plaintiff because it is such an "extreme measure" to place the burden on the defendant. LaMoureaux v. Totem Ocean Trailer Express, Inc., 632 P.2d 539, 545 (Alaska 1981). In LaMoureaux, the court did not find that a compelling injustice had occurred and therefore did not place the burden on the defendant in that case. Id.
. We note that while some courts have combined discussions of the eggshell plaintiff doctrine with shifting the burden of proving apportionment to the defendant when apportionment between new injuries and a preexisting condition is not possible, see, e.g., Newbury v. Vogel, 151 Colo. 520, 379 P.2d 811, 813 (1963), at least one court has also placed the burden on the plaintiff to prove that the apportionment is impossible. See McDonald v. United Airlines, Inc., 365 F.2d 593, 594 (10th Cir.1966).
. We are expressing no opinion on whether the eggshell plaintiff doctrine was inapt in this case because that issue is not before us. Rowe did not claim that she was an eggshell plaintiff. The dissent, however, is incorrect to state conclusively that Rowe did not continue to suffer from back and neck problems before the accident with Munye — in fact, Rowe sought chiropractic treatment only a few days before the accident. Moreover, Rowe’s theory suggests that her injury involves an aggravation of a preexisting injury. If she had been entirely asymptomatic, we would not have the issue before us. See Mor-lock, 650 N.W.2d at 161 (determining that deciding CIVJIG 91.40 issue was not ripe because no party claimed aggravation of a preexisting injury).
. We further note another potential danger in CIVJIG 91.40. The third sentence of CIVJIG *74391.40 instructs the jury, "[i]f you cannot separate damages caused by the preexisting disability or medical condition from those caused by the accident, then (defendant) is liable for all of the damages.” (Emphasis added.) In instructing the jury to determine whether the damages can be apportioned, CIVJIG 91.40 improperly usurps the domain of the judge. "Whether the injury is capable of apportionment is a question of law. Once the trial court finds that the harm can be apportioned, the question of actual apportionment is a question of fact for the jury." Canada by Landy, 567 N.W.2d at 507-08 (internal citations omitted); see also Restatement (Second) of Torts § 434(l)(b).