Parr I of this Article describes the schism in the law of restitution between the quadrationists, who believe that the law of restitution and the law of unjust enrichment form a single square that can be named indifferently from either response or causative event, and the multicausalists, who believe that restitution is the law's response to a number of different causative events. The paper aligns itself with the latter camp, in which, when it comes to the proper identification of the different causative events, there are as many views as there are campers. Most multicausalists nevertheless agree that unjust enrichment is, generically, one of the events which trigger rights to restitution. For them it follows both that there is a law of unjust enrichment and that the law of unjust enrichment is no more than one column in the law of restitution. The question then arises as to how the boundaries of unjust enrichment shall be drawn. Part II argues that the key lies in the exclusivity of categories of causative event and, above all, in the bright line that runs between unjust enrichment and wrongful enrichment. Part III seeks to emphasize that line and to prove the practical necessity of drawing it. Just as some fact situations disclose both a tort and a breach of contract, so some fact situations in which a defendant has received a gain disclose both an unjust enrichment and a wrongful enrichment. That kind of alternative analysis aside, "wrongs " and "unjust enrichments" are generic descriptions of distinct categories of causative events, and a wrong does not become an unjust enrichment merely because it enriches the wrongdoer, nor because the victim comes into court claiming the amount of that wrongful enrichment. Those essential propositions were obscured by the 1937 Restatement and appear not to be fully accepted by the Reporter of the new Restatement now in the making. Six specific arguments are advanced to show that the distinction has to be respected.
