The common law theory of promissory estoppel offers a possible avenue for closing the gap between the civil law concept of cause, which supports enforcement of gratuitous promises, and the common law doctrine of consideration, which does not. Students of U.S. contract law, however, may be surprised to learn that – in contrast to promissory estoppel as an affirmative cause of action in the U.S. – English common law recognizes promissory estoppel only as a defensive shield, except in the limited context of promises relating to ownership of land.
Further inquiry into the enforcement of promises under common law reveals a second surprise to students in the United States, where the legal effect of the sealed instrument is largely abandoned or severely eroded. English common law has never abandoned its modern equivalent of the early action of covenant, but a statute has eliminated the requirement of a seal. A gratuitous promise under deed (a promise in a signed, witnessed, and delivered writing) is fully enforceable in England, arguably bringing English common law closer to the enforcement rules of the French Civil Code than to the common law of the United States.
By including such comparisons in our contracts courses, students can appreciate the noninevitability of the paths taken in the common law. At the same time, they can appreciate the degree to which the common law and civil law have both recognized the need to enforce promises outside the context of an exchange, although they have taken slightly different roads to that destination.