253 Wis.2d 477 (2002) 2002 WI 73 645 N.W.2d 889

Charles STEHLIK and Barbara Stehlik, Plaintiffs-Appellants,
KIMBERLY CLARK CORPORATION and Medicare Part A and Part B, Involuntary-Plaintiffs,
v.
Paul RHOADS, Jill Rhoads, American Standard Insurance Company of Wisconsin and Wilson Mutual Insurance Company, Defendants-Respondents.

No. 99-3326.

Supreme Court of Wisconsin.

Oral argument September 17, 2001. Decided June 26, 2002.

*482 For the plaintiffs-appellants there were briefs by Douglas B. Keberle and Keberle & Patrykus LLP, West Bend, and Owen Thomas Armstrong, Jr. and Quarles & Brady LLP, Milwaukee, and oral argument by Douglas B. Keberle and Owen Thomas Armstrong, Jr.

For the defendants-respondents, Paul and Jill Rhoads and American Standard Insurance Company of Wisconsin, there was a brief by John U. Schmid, Laurie E. Meyer, Paul F. Graves and Borgelt, Powell, Peterson & Frauen, S.C., Milwaukee, and oral argument by Laurie E. Meyer.

For the defendants-respondents, Paul and Jill Rhoads and Wilson Mutual Insurance Company, there was a brief by Joseph J. Voelkner, James O. Conway and Olson, Kloet, Gunderson & Conway, Sheboygan, and oral argument by James O. Conway.

An amicus curiae brief was filed by Werner Erich Scherr and Peterson, Johnson & Murray, S.C., Milwaukee, on behalf of Civil Trial Counsel of Wisconsin.

An amicus curiae brief was filed by Lynn R. Laufenberg and Laufenberg Law Offices, S.C., Milwaukee, on behalf of the Wisconsin Academy of Trial Lawyers.

¶ 1. DIANE S. SYKES, J.

This case involves an all-terrain vehicle (ATV) accident and presents the issue of the availability and effect of the so-called "helmet defense" in Wisconsin. More particularly, the case raises two central questions: 1) is the "helmet defense" governed by the same principles as the "seat belt defense," and if so, should those principles be modified for purposes of the helmet defense; and 2) can an ATV owner be liable for failing to require adult users of the ATV to wear a safety helmet?

*483 ¶ 2. Charles Stehlik sustained serious head injuries in an ATV rollover accident. Paul and Jill Rhoads owned the ATV, and Stehlik was operating it with their permission at a party at their home. Although safety helmets were available, Stehlik was not wearing one at the time of the accident. Stehlik sued the Rhoads for negligence and negligent entrustment. He stipulated, however, that had he "been wearing a safety helmet at the time of his accident he would not have sustained any serious head injury."

¶ 3. The special verdict contained separate questions about the parties' respective causal negligence regarding the accident and regarding Stehlik's failure to wear a helmet. The jury concluded that both the Rhoads and Stehlik were negligent, in both respects, and separately apportioned the accident negligence (70 percent/30 percent) and the "helmet negligence" (60 percent/40 percent) between them. The jury also concluded that 90 percent of Stehlik's injuries were attributable to his failure to wear a helmet.

¶ 4. On motions after verdict, the circuit court struck the special verdict questions regarding the Rhoads' negligence for Stehlik's failure to wear a safety helmet, and limited Stehlik's recovery to the damages attributable to the Rhoads' negligence in causing the accident. That is, the circuit court reduced Stehlik's recovery by his 30 percent accident-causing contributory negligence, and by a further 90 percent—the percentage of his injuries the jury allocated to the failure to wear a helmet. Stehlik appealed, and the court of appeals certified the case to us pursuant to Wis. Stat § 809.61 (1997-98).^[1]

*484 ¶ 5. We conclude that the issue of a plaintiff's negligent failure to wear a safety helmet while operating an ATV is properly governed by the principles applicable to a plaintiff's negligent failure to wear a seat belt established in Foley v. City of West Allis, 113 Wis. 2d 475, 490, 335 N.W.2d 824, 831 (1983). Foley separated the consideration of seat belt negligence from accident negligence and adopted a "second collision" methodology, adapted from successive tort and enhanced injury theories, for the treatment of seat belt negligence.

¶ 6. Unfortunately, however, Foley's "second collision" analysis has had the consequence of entirely removing seat belt negligence (or here, helmet negligence) from the negligence apportionment equation, because it requires the jury to allocate damages, not negligence, when it considers the issue of the plaintiff's seat belt/helmet negligence. In this context, this approach is inconsistent with a liability system grounded upon the idea of comparative responsibility or fault. Accordingly, we now modify the Foley approach for purposes of the helmet defense.

¶ 7. Separate consideration of accident negligence and helmet negligence pursuant to Foley remains the rule. Helmet negligence is a limitation on recoverable damages, not a potential bar to recovery under the comparative negligence statute, Wis. Stat. § 895.045. This aspect of Foley remains sound and is applicable here.

¶ 8. However, for purposes of the helmet defense, we modify Foley's "second collision" construct, at least to the extent that it calls for an allocation of damages rather than an apportionment of negligence on the issue of a plaintiff's helmet negligence. The jury in a helmet defense case should be asked to compare the plaintiff's helmet negligence as against the total combined *485 negligence of the defendants, rather than treating the comparison as an allocation or division of injuries or damages, as in a successive tort or enhanced injury case.

¶ 9. Finally, we conclude that for reasons of public policy, an ATV owner cannot be held liable for failing to require adult users of the ATV to wear an available helmet. The jury in this case should not have been asked to determine whether the Rhoads were negligent in failing to require Stehlik to wear a safety helmet, or to engage in a separate comparison of helmet negligence as between Stehlik and the Rhoads. The circuit court properly struck those questions from the jury verdict in this case.

¶ 10. Because the verdict in this case was based upon Foley, which we have now modified for purposes of the helmet defense, we reverse and remand for a new trial on the issue of liability only.

I

¶ 11. On September 30, 1994, Paul and Jill Rhoads took delivery of a new ATV. Paul Rhoads signed a warranty registration that contained warnings of the various dangers associated with ATVs, including operating the vehicle with passengers, operating without a safety helmet and other protective gear, operating without qualified ATV training, operating under the influence of alcohol, operating on an incline, and allowing others to operate the ATV without having read the owner's manual or received training. Warnings of some of these dangers were also posted on stickers over the front wheel guards, the back wheel guards, the rear bumper, and on the back of the seat of the ATV.

¶ 12. The next day, the Rhoads had a party at their home. They permitted their guests to operate the *486 ATV after dark, on an unlit trail on a hill, with passengers, without instructions, without wearing available safety helmets, and after serving them alcoholic beverages.

¶ 13. Charles Stehlik, a guest who had been drinking alcohol both prior to and during the Rhoads' party,^[2] decided to take the ATV for a ride. Stehlik was an over-the-road truck driver and part-time law enforcement officer for the Washington County Sheriff's Department and the Slinger Police Department. In addition to his employment-related driving experience, Stehlik had racing experience as a modified stock car racer and also drove motorcycles and mopeds. The parties stipulated that the Rhoads owned safety helmets, and the jury found that a helmet was in fact available for Stehlik's use. Nevertheless, Stehlik did not wear a helmet while driving the Rhoads' ATV.

¶ 14. Initially Stehlik operated the ATV alone, but later gave several passengers a ride, including, at the time of the accident, a four-year-old child.^[3] With Stehlik driving and the child aboard sitting in front of him, the ATV rolled over on the side of a hill. Stehlik struck his head against a concrete wall and sustained serious head injuries.

¶ 15. Stehlik sued the Rhoads. Prior to trial, the parties entered into the following stipulation: "The parties have stipulated that had Mr. Stehlik been wearing a safety helmet at the time of his accident he would *487 not have sustained any serious head injury. The parties have also stipulated that Paul and Jill Rhoads owned such safety helmets."

¶ 16. The jury found both the Rhoads and Stehlik causally negligent with respect to the accident. The jury apportioned 70 percent of the accident negligence to the Rhoads and 30 percent to Stehlik. The jury also determined that a safety helmet was available for Stehlik's use, and that both the Rhoads and Stehlik were negligent with respect to Stehlik's failure to wear a helmet. The jury apportioned 60 percent of this "helmet negligence" to the Rhoads and 40 percent to Stehlik. The jury determined that 90 percent of Stehlik's injuries were attributable to his failure to wear a helmet. The jury fixed Stehlik's damages at $853,277.^[4]

¶ 17. On motions after verdict, the Washington County Circuit Court, the Honorable Annette K. Ziegler, concluded that the helmet negligence was passive negligence not subject to a comparative negligence analysis, and so the special verdict questions pertaining to the Rhoads' negligence regarding Stehlik's failure to wear a safety helmet should not have been submitted to the jury. The court struck those questions from the special verdict and reduced Stehlik's damages by 90 percent (the amount attributable to his failure to wear a helmet), and by a further 30 percent (the amount of his contributory negligence in causing the accident), resulting in an ultimate damages award of $54,198. Stehlik appealed, and the court of appeals certified the case to us.

*488 II

[1]

¶ 18. We review the circuit court's decision regarding the postverdict motions de novo because it presents a question of law. See Danner v. Auto-Owners Insurance, 2001 WI 90, ¶ 41, 245 Wis. 2d 49, 65, 629 N.W.2d 159, 168. The Rhoads moved, pursuant to Wis. Stat. § 805.14(5), for an order striking the special verdict questions regarding their liability for helmet negligence, although they did not contend that the evidence was insufficient to sustain the answers. See Wis. Stat. § 805.14(5)(c). Rather, they argued that as a matter of law, they could not be liable for the helmet negligence of another. Therefore, while the postverdict motions were not styled as motions for judgment notwithstanding verdict (JNOV), the de novo standard of review, applicable to decisions on JNOV motions, applies here. See Herro v. DNR, 67 Wis. 2d 407, 413, 227 N.W.2d 456 (1975)("While not challenging the sufficiency of the evidence to support the facts found in the verdict, [a JNOV motion] may be used to challenge whether the facts found in the verdict are [legally] sufficient to permit recovery.").

III

[2]

¶ 19. This case was submitted to the jury on negligence and negligent entrustment theories.^[5] We note initially that the jury was improperly instructed on the negligent entrustment theory of liability. The circuit court used the pattern jury instruction applicable *489 to negligent entrustment cases under § 308 of the Restatement, which was adopted by this court in Bankert v. Threshermen's Mutual Ins. Co., 110 Wis. 2d 469, 476, 329 N.W.2d 150 (1983). See Wis JI—Civil 1014; Restatement (Second) of Torts § 308 (1965). The court of appeals has held, however, that § 308 is not applicable to self-inflicted injuries such as Stehlik's. See Erickson v. Prudential Ins. Co., 166 Wis. 2d 82, 95, 479 N.W.2d 552 (Ct. App. 1991).

¶ 20. Section 308 of the Restatement (Second) of Torts provides:

§ 308 Permitting Improper Persons to Use Things or Engage in Activities

It is negligence to permit a third person to use a thing or to engage in an activity which is under the control of the actor, if the actor knows or should know that such person intends or is likely to use the thing or to conduct himself in the activity in such a manner as to create an unreasonable risk of harm to others.

Restatement (Second) of Torts § 308 (emphasis added). In Erickson, the court of appeals held that § 308, by its terms, applies only when the person who is negligently entrusted with an item or activity injures someone else, not himself. Erickson, 166 Wis. 2d at 95. Here, however, the circuit court modified the pattern jury instruction applicable to § 308, Wis JI—Civil 1014, to conclude with the phrase "unreasonable risk of harm to himself" instead of "unreasonable risk of harm to others," contrary to Erickson.

¶ 21. The negligent entrustment theory at issue in this case appears in § 390 of the Restatement:

§ 390 Chattel for Use by Person Known to be Incompetent

One who supplies directly or through a third person a chattel for the use of another whom the supplier knows *490 or has reason to know to be likely because of his youth, inexperience, or otherwise, to use it in a manner involving unreasonable risk of physical harm to himself and others who the supplier should expect to share in or be endangered by its use, is subject to liability for physical harm resulting to them.

Restatement (Second) of Torts § 390 (1965). This section of the Restatement was adopted by the court of appeals in Halverson v. Halverson, 197 Wis. 2d 523, 530, 541 N.W.2d 150 (Ct. App. 1995). However, there is no pattern jury instruction for use in § 390 cases.

¶ 22. The two theories of negligent entrustment are related but not identical. The commentary to § 390 explains that "[t]he rule stated in this Section is a special application of the rule stated in § 308 . . . . This Section deals with the supplying of a chattel to a person incompetent to use it safely . . . ." Restatement (Second) of Torts § 390, cmt. b. Had the jury been instructed on § 390, it might have concluded that because Stehlik was a professional driver and part-time law enforcement officer experienced in stock car racing, motorcycle, and moped driving, he was not incompetent to use the ATV safely and therefore the Rhoads were not negligent in entrusting him with it. On the other hand, the jury might have concluded that the Rhoads were negligent in entrusting their ATV to Stehlik because he had been drinking and was therefore incompetent to use it safely.

¶ 23. A § 308 claim is a bit broader, and can be asserted any time the circumstances are such that the defendant knew or should have known that the person to whom he is entrusting an item is likely to use it in a way that creates an unreasonable risk of harm to others. But § 308 has never been extended to cases such as this one involving self-inflicted harm by the one to *491 whom an item is allegedly negligently entrusted. In fact, as noted above, Erickson specifically held that it does not apply to such cases. Erickson, 166 Wis. 2d at 95.

¶ 24. The distinction noted here may not have made a difference on the facts of this case, and no one raised the issue on appeal. We address it because we are remanding for a liability retrial, and to emphasize that this case should not be construed as a sub silentio overruling of Erickson or an extension of § 308 to cases involving self-inflicted injuries. In addition, this discussion has a bearing on our analysis of the liability of an ATV owner for an adult ATV user's failure to wear an available helmet. See infra Part V.

IV

¶ 25. The parties dispute whether, and to what extent, the principles applicable to the so-called "seat belt defense" also govern the "helmet defense" asserted here. The seat belt defense was first recognized in Bentzler v. Braun, 34 Wis. 2d 362, 385, 149 N.W.2d 626 (1967).

¶ 26. In Bentzler, this court concluded that the common law duty to exercise ordinary care for one's own safety contemplated the use of available seat belts to protect against serious injury in an automobile accident. Id. The court reached this conclusion "independent of any statutory mandate," id., because of the common knowledge, supported by statistical evidence, that seat belts save lives and reduce injury:

While it is apparent that these statistics cannot be used to predict the extent or gravity of injuries resulting *492 from particular automobile accidents involving persons using seat belts as compared to those who are not using them, it is obvious that, on the average, persons using seat belts are less likely to sustain injury and, if injured, the injuries are likely to be less serious. On the basis of this experience, and as a matter of common knowledge, an occupant of an automobile either knows or should know of the additional safety factor produced by the use of seat belts. A person riding in a vehicle driven by another is under the duty of exercising such care as an ordinarily prudent person would exercise under similar circumstances to avoid injury to himself.

Id. at 386-87.

¶ 27. The Bentzler analysis of the seat belt defense logically and conceptually applies to the helmet defense asserted in this case. Significantly, the absence of a statute mandating seat belt use was not decisive in Bentzler; nor is the absence of a statute mandating helmet use by adult ATV riders decisive here.^[6] In this context, as in Bentzler, the safety benefits of wearing a helmet while operating or riding a non-enclosed vehicle such as an ATV are a matter of common knowledge, supported by statistical evidence.^[7]

*493 [3]

¶ 28. ATVs are, after all, open-air, motorized vehicles capable of reaching moderate to high speeds, and are, by design, intended to be operated on all types of off-road terrain. See Gregory B. Rodgers, All-Terrain Vehicle Injury Risks and the Effects of Regulation, 25 Accident Analysis & Prevention 335-346 (1993). The risks associated with ATVs are well-known. See James C. Helmkamp, A Comparison of State-Specific All-Terrain Vehicle Related Death Rates, 1990-1999, 91 Am. J. Pub. Health 1792-1795 (2001). Under these circumstances, an ordinarily prudent person knows or reasonably should know that wearing a safety helmet while operating or riding an ATV protects against serious head injury. Accordingly, consistent with the rationale of Bentzler, we conclude that the common law duty of ordinary care for one's own safety can encompass the use of a safety helmet while operating or riding an ATV.^[8]

*494 [4]

¶ 29. We caution that the failure to wear a safety helmet while on an ATV, like the failure to wear a seat belt while in an automobile, is not negligence per se:

Failure to wear seat belts is not negligence per se, but "where seat belts are available and there is evidence before the jury indicating [a] causal relationship between the injuries sustained and the failure to use seat belts, it is proper and necessary to instruct the jury in that regard. A jury in such case could conclude that an occupant of an automobile is negligent in failing to use seat belts."

Foley, 113 Wis. 2d at 483 (quoting Bentzler, 34 Wis. 2d at 387). The helmet defense recognized here, like the seat belt defense recognized in Bentzler, is generally a question for the jury.^[9]

¶ 30. The effect of the seat belt defense on liability and damages was addressed 16 years after Bentzler in Foley. There, this court distinguished "seat belt negligence" from active and passive negligence and separated the jury's consideration of seat belt negligence from the basic comparison of negligence, establishing *495 it instead as a limitation on recoverable damages. Foley, 113 Wis. 2d at 484-90.

¶ 31. Foley described the distinction between active, passive, and seat belt negligence in this way:

This court has used the term "passive negligence" to describe the conduct of a passenger who fails to use ordinary care for his or her own safety where the passenger's conduct is found to be a cause of his or her injury but not of the collision. Active negligence describes a person's conduct in failing to use ordinary care when that conduct is a cause of the collision. A passenger can be found both actively and passively negligent, depending on the circumstances. Theisen v. Milwaukee Automobile Mut. Ins. Co., 18 Wis. 2d 91, 105, 118 N.W.2d 140 (1962).

It is true that failure to use available seat belts in this case (and in the ordinary case) is not a cause of the collision and would thus appear to fall within the category "passive negligence," but we decline to label seat-belt negligence as "passive" negligence because the seat-belt defense doctrine rests on considerations different from those involved in "passive negligence."

In the usual case of passive negligence, the passenger could have prevented injury completely by taking some action: e.g. refusing to ride with that particular driver at that particular time, or warning of a hazard. In contrast, a passenger who wears a seat belt can not usually avoid all injury. Since failure to wear seat belts generally causes incremental injuries, damage for these incremental injuries can be treated separately for purposes of calculating recoverable damages. In contrast injuries caused by passive negligence are identical to injuries caused by the active negligence in the same accident, and the damages due to passive negligence can not be separated easily for purposes of calculating recoverable damages. *496 Id. at 484-85.

¶ 32. Foley then analogized a seat belt defense case to one involving successive torts:

To understand the distinction between passive negligence and the [sic] seat-belt negligence, it is helpful to think of the automobile accident involving seat-belt negligence as involving not one incident but two. The first incident is the actual collision, in this case the two cars hitting each other. The second incident, which is set in motion by the first and would not occur without it, occurs when the occupant of the vehicle hits the vehicle's interior . . . . Wearing seat belts is relevant only to the second collision and, as discussed above, may aggravate some of the damages caused by the first collision. Failure to wear seat belts may also cause additional injuries. Negligence and damages can be apportioned between the two incidents.

Since seat-belt negligence and passive negligence are distinguishable, we must determine whether seatbelt negligence should be treated differently from passive negligence. As a general rule, when there is a logical basis to allocate damages between two or more incidents and among various parties, courts attempt to do so . . . . Accordingly, since damages can be allocated in a seat-belt defense case between the collision and the seat-belt negligence, we should attempt to do so. Unlike the circuit court, which combined the two types of negligence, we conclude that a fair and administrable procedure, taking into account the public policy underlying the seat-belt defense and the principles of comparative negligence enunciated in sec. 895.045, is to calculate a plaintiff's provable damages by the usual rules of negligence without regard to the seat-belt defense and then take into account the seat-belt defense by decreasing the recoverable damages by the percentage of the plaintiff's causal seat-belt negligence.

Id. at 485-87 (citations omitted).

*497 ¶ 33. Foley's analysis—separating the jury's consideration of a plaintiff's seat belt negligence from its consideration of accident negligence—"borrows from the apportionment technique used in two traditional tort doctrines: avoidable consequences and mitigation of damages." Id. at 487. Establishing seat belt negligence as a separate limitation on recoverable damages "treat[s] the plaintiff and defendant in such a way that the plaintiff recovers damages from the defendant for the injuries that the defendant caused, but . . . the defendant is not held liable for incremental injuries the plaintiff could and should have prevented by wearing an available seat belt." Id. at 489.

¶ 34. Foley prescribed the following general procedure for the judge and jury in a seat belt defense case:

(1) Determine the causal negligence of each party as to the collision of the two cars . . . (2) apply comparative negligence principles to eliminate from liability a defendant whose negligence causing the collision is less than the contributory negligence of a plaintiff causing the collision . . .; (3) using the trier of fact's calculation of the damages, reduce the amount of each plaintiff's damages from the liable defendant by the percentage of negligence attributed to the plaintiff for causing the collision . . .; (4) determine whether the plaintiff's failure to use an available seat belt was negligence and a cause of injury, and if so what percentage of the total negligence causing the injury was due to the failure to wear the seat belt . . .; (5) reduce the plaintiff's damages calculated in step (3) by the percentage of negligence attributed to the plaintiff under step (4) for failure to wear an available seat belt for causing the injury.

Foley, 113 Wis. 2d at 490.

¶ 35. The fourth and fifth steps in the process appear to require an apportionment of seat belt negligence as against total injury-causing negligence, and a *498 corresponding reduction in damages. However, if Foley is understood as applying a modified successive tort or incremental injury analysis, then what was meant is not an apportionment of negligence at all, but an allocation or division of injuries or damages among distinct causes (the accident and the failure to wear a seat belt), and an accompanying reduction in the plaintiff's recovery.

¶ 36. Indeed, language at the end of the Foley opinion refers to the court as having established "the proper method for apportioning damages in seat-belt negligence cases." Id. at 496 (emphasis added). The court also invited the Wisconsin Civil Jury Instruction Committee to draft an instruction that requires the jury to fix the "percentage of total damages" attributable to the plaintiff's failure to wear a seat belt. Id. at 495 (emphasis added).

¶ 37. Accordingly, the fourth step in the Foley process ordinarily involves a determination of whether the plaintiff's failure to wear a seat belt was negligence, and if so, what percentage of the plaintiff's total injuries or damages were attributable to the failure to wear a seat belt. The fifth step calls for a reduction in the plaintiff's recovery by that percentage. See Wis JI— Civil 1722A (successive torts), 1723 (enhanced injuries). This is how the circuit court understood and applied the Foley procedure here.^[10]

¶ 38. It is also how the legislature appears to have understood the Foley methodology. In 1987, four years after Foley, the legislature enacted a law mandating seat belt use, and included a 15 percent cap on the *499 amount by which a plaintiffs recovery can be reduced for failure to wear a seat belt under the Foley analysis:

. . . .

§ 347.48(2m) Required use.

. . . .

(g) Evidence of compliance or failure to comply with par. (b), (c) or (d) [requiring seat belt use] is admissible in any civil action for personal injuries or property damage resulting from the use or operation of a motor vehicle. Notwithstanding s. 895.045 [the comparative negligence statute], with respect to injuries or damages determined to have been caused by a failure to comply with par. (b), (c) or (d), such a failure shall not reduce the recovery for those injuries or damages by more than 15%. This paragraph does not affect the determination of causal negligence in the action.

Wis. Stat. § 347.48(2m)(g).

¶ 39. In Gaertner v. Holcka, 219 Wis. 2d 436, 580 N.W.2d 271 (1998), this court analyzed the effect of the statutory change as follows:

By amending Wis. Stat. § 347.48, the legislature explicitly adopted our interpretation of the seat belt defense. Significantly, the legislature sought to preserve Foley's attempt to prevent defendants from attaining a windfall by indicating that "this paragraph does not affect the determination of causal negligence in the action." See Wis. Stat. § 347.48(2m)(g). As it is relevant to this opinion, the legislature modified the common law . . . to limit to 15% the potential reduction in plaintiffs' recoverable damages.

Gaertner, 219 Wis. 2d at 450.

¶ 40. Foley's "second collision" successive tort theory of seat belt negligence is analogous to enhanced injury case law that has developed in the product *500 liability context. See generally Sumnicht v. Toyota Motor Sales, U.S.A, Inc., 121 Wis. 2d 338, 352-60, 360 N.W.2d 2 (1984); Farrell v. John Deere Co., 151 Wis. 2d 45, 64-67, 443 N.W.2d 50 (Ct. App. 1989); Wis JI—Civil 1723; see also Wis JI—Civil 1722A. Enhanced injury cases draw upon a "second collision" or successive tort analysis in an attempt to fairly allocate responsibility for a plaintiff's damages where there is proof of distinct injury-producing causes converging in the same accident. See Restatement (Third) of Torts § 26 (2000).

[5]

¶ 41. Applying a modified successive tort or "second collision" theory to a single accident case may make sense when it involves the allocation or division of injuries or damages among demonstrably distinct causes for which different defendants might be responsible. But applying it to the issue of a plaintiff's seat belt or helmet negligence operates to deprive the plaintiff of a jury comparison of the fault associated with his failure to wear a seat belt (or here, a helmet) as against the total fault or responsibility that combined to cause the whole of his injuries or damages.

¶ 42. This aspect of Foley has been criticized as generating "problems of fairness and consistency," in that the relative culpability associated with seat belt nonuse is never weighed against the relative culpability of the accident-causing tortfeasor. Michael K. McChrystal, Seat Belt Negligence: The Ambivalent Wisconsin Rules, 68 Marq. L. Rev. 539, 542, 547 (1985). Highly aggravated accident-causing negligence might in a given case substantially outweigh the negligence associated with the failure to wear a seat belt or helmet.^[11]*501 But under Foley, the jury does not apportion negligence when it considers the seat belt or helmet defense, it allocates or divides damages, which is a substantially different inquiry.

¶ 43. As Justice Bradley noted in her concurrence in Gaertner, "in attempting to partition the seat belt negligence away from the primary tortfeasor's negligence, it appears that the Foley court may have also partitioned the primary tortfeasor's negligence away from the seat belt negligence in determining responsibility for enhanced injuries. The Foley court seems to have immunized initial tortfeasors from the full consequences of their negligence." Gaertner, 219 Wis.2d at 462 (Bradley, J., concurring.) That is, "a tortfeasor whose conduct caused the initial collision and whose negligent conduct may be a substantial casual factor of the victim's enhanced injuries is not credited with any responsibility for those injuries." Id. at 461. In the context of the seat belt defense, the legislature has minimized the potential practical effect of this conceptual problem by imposing a statutory 15 percent cap on the amount by which a plaintiff's recovery can be reduced for failure to wear a seat belt.

[6,7]

¶ 44. We conclude that, as applied to the helmet defense, Foley's modified successive tort conceptualization, which in this situation would call for an allocation of helmet injury or damages to the plaintiff regardless of total relative culpability or fault, is inconsistent with a liability system based upon the idea of comparative responsibility. But for the defendants' accident negligence, *502 the plaintiff would not have sustained any injury at all, whether "helmet injury" or otherwise (assuming, of course, that the plaintiff's own accident negligence does not exceed the defendants'). For this reason, the determination of the amount by which the plaintiff's recovery should be reduced because of his own helmet negligence should take the accident negligence of the defendants into consideration. For purposes of applying Foley to the helmet defense, we decline to adopt the modified successive tort concept from the opinion's overall methodology.^[12]

[8]

¶ 45. The jury in a helmet defense case should determine and apportion accident negligence separately from helmet negligence. Only the former is subject to