1859: First Temporary Insanity Defense in U.S.

(Wikipedia) ... Sickles's career was replete with personal scandals. He was censured by the New York State Assembly for escorting a known prostitute, Fanny White, into its chambers. He also reportedly took her to England, leaving his pregnant wife at home, and presented White to Queen Victoria, using as her alias the surname of a New York political opponent.
In 1859, in Lafayette Square, across the street from the White House, Sickles shot and killed the district attorney of the District of Columbia Philip Barton Key II, son of Francis Scott Key, who Sickles had discovered was having an affair with his young wife.  Continued