(concurring in part; dissenting in part). I agree with the majority's holding that du Pont is not responsible, as a matter of law, under a strict-liability or negligence theory. I disagree with its holding that Westphal's negligence action against Dr. Litow was untimely. Robinson v. Mount Sinai Medical *376Ctr., 137 Wis. 2d 1, 28-29, 402 N.W.2d 711, 722 (1987), spells out the continuous-negligent-treatment test established in Tamminen v. Aetna Casualty & Sur. Co., 109 Wis. 2d 536, 327 N.W.2d 55 (1982). The question is "whether a layperson could reasonably conclude that the facts fall within a single unit or occurrence." Robinson, 137 Wis. 2d at 27, 402 N.W.2d at 722 (emphasis added). The test is objective, and the Robinson court applied it to the pleaded facts to reach an answer as a matter of law. Because the test looks to what "a layperson could reasonably conclude," it should be liberally rather than strictly applied. The elements of the test are (1) continuous care, (2) continuous negligent medical care, (3) the medical care related to a single condition, and (4) the precipitating factor in the continuum was the original act of malpractice. Id. at 28-29, 402 N.W.2d at 722.
The majority confines its discussion to the second element, whether the negligent conduct was continuous. The majority states "that the amount of time that has passed between each allegedly negligent act is necessarily a primary factor in determining whether there has been a continuum of negligent treatment . . . ." Majority op. at 373-374 (emphasis added). Why the amount of time is "necessarily a primary factor" is not explained. The implication is that there may be other "primary" factors but the majority relies only on the passage of time between Dr. Litow's operation on November 10, 1982, and Dr. Messer's operation on December 13,1984. Nor does the majority explain why the passage of about two years, without more, requires our holding that the second element, continuous negligent medical care, is unsatisfied.
To conclude that the negligent treatment was not continuous when about two years intervened between *377the allegedly negligent acts establishes a bright-linej test. However, I do not read the case law to mean that in all circumstances an interval of a certain period, without more, destroys the continuity of negligent medical care.
We ought not conclude that the two-year interval interrupts what would otherwise have been continuous negligent medical treatment. First, Dr. Litow's work did not stop with his November 10, 1982 operation on Westphal. In October 1983 and in March 1984, he inserted TMJ implants in Westphal's left and right TMJ's. That those insertions were not negligently performed is immaterial. A reasonable person in Westphal's position could have waited until well after those insertions to decide whether to commence an action against Dr. Litow for medical malpractice based on his November 10, 1982 surgery. Second, about eight-and-one-half months passed between Dr. Litow's last implant insertion in March 1984 and Dr. Messer's allegedly negligent procedure on December 13,1984. A reasonable person could have waited to determine whether Dr. Messer's procedure rectified the medical problem. For those reasons, a layperson could reasonably conclude that the facts fall within a single unit or occurrence. I therefore conclude that the time between the first and second acts of alleged negligence is not such as to destroy the continuity of negligent treatment.
If it is desirable to establish a bright-line test to determine whether the time between acts of medical negligence destroys the continuity of the negligence, we should look to the medical-malpractice statute of limitations, § 893.55, STATS., for guidance. Section 893.55(l)(a) establishes a three-year limitation. Three years had not elapsed between the allegedly negligent *378acts of Drs. Litow and Messer. Looking to the statute of limitations is arbitrary to the extent that the choice of any fixed period of time is arbitrary. The statute provides, however, a useful analogy because the legislature itself has fixed the time in which a person should start an action. The statutory analogy provides a rational basis on which to base the decision. The mere passage of about two years, without more, does not provide that basis.
We should hold that a continuum of negligent medical care exists in this case. It is undisputed that a continuum of care existed, the medical care related to a single condition and the precipitating factor in the continuum was the initial decision by Dr. Litow to operate in November 1982. We therefore should hold that the course of conduct here is such that a "layperson could reasonably conclude that the facts fall within a single unit or occurrence," Robinson, 137 Wis. 2d at 27, 402 N.W.2d at 722, and that Westphal's action was timely brought against Dr. Litow.