Billings Learned Hand (January 27, 1872 – August 18, 1961; middle name pronounced /ˈlɜrnɨd/ LERN-id) was a United States judge and judicial philosopher. He served on the United States District Court for the Southern District of New York and later the United States Court of Appeals for the Second Circuit. Hand has been quoted more often than any other lower-court judge by legal scholars and by the Supreme Court of the United States.

Born and raised in Albany, New York, Hand majored in philosophy at Harvard College and graduated with honors from Harvard Law School. After a short career as a lawyer in Albany and New York City, he was appointed as a Federal District Judge in Manhattan in 1909 at the age of 37. The profession suited his detached and open-minded temperament, and his decisions soon won him a reputation for craftsmanship and authority. Between 1909 and 1914, under the influence of Herbert Croly's social theories, Hand supported New Nationalism. He ran unsuccessfully as the Progressive Party's candidate for Chief Judge of the New York Court of Appeals in 1913, but withdrew from active politics shortly afterwards. In 1924, President Calvin Coolidge promoted Hand to the Court of Appeals for the Second Circuit, which he went on to lead as the Senior Circuit Judge (later retitled Chief Judge) from 1939 until his semi-retirement in 1951. Scholars have recognized the Second Circuit under Hand as one of the finest appeals courts in the country's history. Friends and admirers often lobbied for Hand's promotion to the Supreme Court, but circumstances and his political past conspired against his appointment.

Hand possessed a gift for the English language, and his writings are admired as legal literature.[2] He rose to fame outside the legal profession in 1944 after giving a short address in Central Park that struck a popular chord in its appeal for tolerance. During a period when a hysterical fear of subversion divided the nation, Hand was viewed as a liberal defender of civil liberties. A collection of Hand's papers and addresses, published in 1952 as The Spirit of Liberty, sold well and won him new admirers. Even after he criticized the civil-rights activism of the 1950s Warren Court, Hand retained his popularity.

Hand is also remembered as a pioneer of modern approaches to statutory interpretation. His decisions in specialist fields, such as patents, torts, admiralty law, and antitrust law, set lasting standards for craftsmanship and clarity. On constitutional matters, he was both a political progressive and an advocate of judicial restraint. He believed in the protection of free speech and in bold legislation to address social and economic problems. He argued, however, that the United States Constitution does not empower courts to overrule the legislation of elected bodies, except in extreme circumstances. Instead, he advocated the "combination of toleration and imagination that to me is the epitome of all good government".