Black's Law Dictionary is the most widely used law dictionary in the United States. It was founded by Henry Campbell Black (1860–1927). It is the reference of choice for terms in legal briefs and court opinions and has been cited as a secondary legal authority in many U.S. Supreme Court cases.[citation needed]

The latest editions, including abridged and pocket versions, are useful starting points for the layman or student when faced with an unfamiliar legal term.