vagueness doctrine
The vagueness doctrine is a constitutional principle requiring that laws be written with sufficient clarity so that ordinary people can understand what conduct is prohibited and so that enforcement is not arbitrary or discriminatory. A law that fails to meet this standard may be declared void for vagueness. The doctrine rests on the Due Process Clauses of the Fifth and Fourteenth Amendments. The Supreme Court has explained that individuals should not be required to guess at a law’s meaning or experience inconsistencies in its application. See Winters v. New York, 333 U.S. 507 (1948).
The vagueness doctrine serves two primary purposes: providing fair notice to individuals and preventing arbitrary or discriminatory enforcement by limiting the discretion of law enforcement and courts. Although the doctrine most commonly arises in the context of criminal statutes, it also applies to civil laws that impose penalties or regulate conduct.
The doctrine is related to, but distinct from, the overbreadth doctrine, which addresses laws that prohibit a substantial amount of protected conduct.
[Last reviewed in April of 2026 by the Wex Definitions Team]
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