Academic journal article Notre Dame Law Review

Ex-Post Right, Ex-Ante Wrong

Academic journal article Notre Dame Law Review

Ex-Post Right, Ex-Ante Wrong

Article excerpt


Should a doctor be held liable under negligence law for harmful treatment she administered to a patient, if the treatment should have been considered negligent at the time it was administered, but is now considered reasonable at the time of trial? Should a manufacturer be held liable for harm caused to a consumer from a product that is considered reasonable, and therefore non-defective, at the time of trial, but that should have been considered unreasonable, and therefore defective, at the time of its distribution ? More generally put: Should the law impose liability for ex-post right but ex-ante wrong behaviors? The answer offered by this Article is yes, on both efficiency and corrective justice grounds. The Article also proposes the adoption, in certain cases, of an "alternative liability rule, " whereby an injurer bears liability if his behavior is either ex-post or ex-ante wrong.

Thus far, there are no reported cases where a plaintiff brought suit for ex-post reasonable but ex-ante unreasonable behavior or products. This is puzzling, especially given the abundance of reverse cases before the courts, where the defendant's behavior or product is found to be ex-post unreasonable but ex-ante reasonable, and liability is not imposed. The Article's explanation for the lack of suits for ex-post right but ex-ante wrong behavior is plaintiffs' and their attorneys' strong belief that when a behavior, or a product, is considered reasonable at the time of trial, it is considered reasonable by the law. The claim made in the Article is that this belief is unfounded and a plaintiff who proves ex-ante negligence should succeed at trial, regardless of whether the defendant's behavior is considered reasonable at that time.


Injurers often do the wrong thing, which, in retrospect, turns out to be the right thing. Should they be held liable under current law if the ex-ante wrong but ex-post right behavior caused harm to a victim? This fundamental question, relevant to many legal fields, has never been given any clear answer, neither in the case law nor in scholarly writings. This Article offers an affirmative answer: yes, injurers should be held liable for ex-post right behavior if that behavior was ex-ante wrong. The Article also proposes and explores an innovative rule, termed the alternative liability rule, under which an injurer bears liability if his behavior is either ex-post or ex-ante wrong, showing that under certain conditions, which are often met in product liability cases, this is the optimal liability rule.

To illustrate the problem addressed in this Article, assume that a doctor must decide whether to operate on her patient. The doctor considers the reasonably available information about the patient's medical condition and negligently chooses not to operate. A few days later, the risk entailed by the doctor's decision not to operate materializes into harm. At that point, however, new information emerges that clearly indicates that given the ex-ante risks of operating versus not operating, the doctor's behavior was reasonable. Should the patient be allowed to recover, under negligence law, for the harm he suffered due to the doctor's ex-ante negligent but ex-post reasonable behavior?

A similar question may arise in any legal context where reasonableness is a criterion for liability (or defense). Consider the following example from products liability law: Suppose that a manufacturer of cellular phones is being sued by a consumer for harms caused by radiation from the phone. Assume that according to the information available at the time of the trial, the phones emit very low-risk radiation; therefore the way that the manufacturer produced its product--according to the same information--is considered reasonable and the product non-defective. Should the consumer, who suffered harm from the radiation, succeed at trial if she can show that according to the information that was reasonably available at the time of the product's distribution, the manufacturer should have suspected--erroneously, in retrospect--the radiation to be far riskier than what it actually is and, therefore, the product should be considered defective? …

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