1859: First Temporary Insanity Defense in U.S.

(Wikipedia) Daniel Edgar Sickles (October 20, 1819 – May 3, 1914) was a colorful and controversial American politician, Union General in the American Civil War, and diplomat.
As an antebellum New York politician, Sickles was involved in a number of public scandals, most notably the killing of his wife's lover, Philip Barton Key, son of Francis Scott Key. He was acquitted with the first use of temporary insanity as a legal defense in U.S. history. He became one of the most prominent political generals of the Civil War. At the Battle of Gettysburg, he insubordinately moved his III Corps to a position in which it was virtually destroyed, an action that continues to generate controversy. His combat career ended at Gettysburg when his leg was struck by cannon fire. Continued