Every term of art in the law that can harm human beings ought to be intelligible. Courts, legislatures as statute-writers, and scholars improve clarity when they explain and reassess high-stakes legal concepts. One such concept has escaped that attention. The United States Supreme Court wrote the presumption of innocence into constitutional criminal procedure; the phrase fills conversation around the world. But what is it for? Judicial decisions, statutes, scholarship, and lay discourse have left its meanings elusive.

Superficial benevolence in the term might explain this indifference to precision. Ascribing innocence seems gentle; “presumption” sounds logical. In application, however, purporting to presume innocence imposes plenty of harmful consequences, and rarely with any logic or rigor.

Time for clarity. The presumption of innocence is an instrument deployable toward desirable ends, rather than a desirable end in itself. It can have both good and bad effects. While harm derived from misapplication of this presumption has its fullest record in one setting, the reception of sexual misconduct accusations, the risk of epistemic injustice that it brings to factfinding is present anywhere individuals accuse and are accused. The presumption of innocence ought to be granted and withheld in proper measure.