103 Iowa L. Rev. 245 (2017)
If a police officer searches my home illegally and finds evidence of a crime there, the criminal law suppresses not only that evidence, but evidence derived from the search that was not itself found illegally. This doctrine is known as the “fruit of the poisonous tree.” The animating principle of the fruit of the poisonous tree doctrine is but-for causation: If you had not violated the law, you wouldn’t have found the evidence, and so you wouldn’t have followed whatever investigative path was triggered by the finding of that evidence. The newly discovered evidence—the fruit—is tainted by the poison of the illegal search.
Intellectual property (“IP”) regimes face this issue when defendants infringe an IP right in the course of making a product that does not itself infringe that right. IP law is all over the map in dealing with such cases. Some IP regimes, like trade secret law, apply the fruit of the poisonous tree logic, allowing the plaintiff to recover not only for the profits the defendant made from secrets she actually stole and used but also for the profits of any product that resulted from the use of those secrets. Copyright law, by contrast, does not permit a plaintiff either to obtain an injunction or to recover damages against non-infringing final products. Patent law is somewhere in between.
In this Essay, I offer a cohesive way to think about the fruit of the poisonous tree in IP law. Whether IP remedies should extend to tainted but noninfringing products should be a function of the mental state of the infringer, the likelihood that infringement will be detected, and the contribution made by the final, non-infringing product. Balancing those three factors won’t necessarily lead all IP regimes to treat the fruit of the poisonous tree in the same way. But it does both explain and suggest some needed reforms to the current legal rules.