This paper considers the history and nature of the ‘modern rule of releases’, concerning compromises to settle or preclude litigation. The rule holds that only matters the parties had contemplated as well as what they intended to release will in fact be released, even if the compromise has been made in the most general terms. Thus the rule is engaged when the releasor executes a general release but does not appreciate the existence of some of the claims the words used purport to release. This paper shows how the rule is a confusion of different conceptual bases and lines of authority and was created by accidentally muddling them together. It argues that, despite this, it successfully straddles both bases, functions well conceptually and serves a vital role.