Afoul

Afoul is an adjective and adverb used to indicate that someone or something is in conflict with or in violation of rules, laws, or policies. The most common construction is the phrasal verb run afoul of, as in “the company ran afoul of environmental regulations.” In this sense, afoul implies more than disagreement; it denotes a breach or noncompliance that may invite penalties, corrective action, or enforcement. Afoul of can also modify a noun in phrases such as “afoul of the law,” to describe someone who has violated legal or regulatory standards. The term is often found in legal, regulatory, and formal writing, and it carries a somewhat traditional or authoritative tone.

Etymology and history: The word derives from nautical language. Foul describes entanglement or obstruction, and to run afoul of something meant to come into contact with it in a troublesome way. Over time, the sense broadened beyond ships and the sea to include nonnautical conflicts with rules or norms. The expression appears in English in the early modern period and has since become a standard idiom for signaling noncompliance or conflict with guidelines.

Usage notes: While common in formal or legal contexts, the phrase may sound old-fashioned in casual speech. Alternatives include in violation of, contravening, infringing, or running afoul of the rules. It is most often used with institutions or standards such as the law, regulations, policies, or contractual provisions.

Examples: The project ran afoul of zoning regulations. The company faced penalties after running afoul of emission standards. The driver was cited for running afoul of safety rules.