1859
A few blocks from the White House, New York congressman Daniel Edgar Sickles fired three shots into D.C. district attorney Philip Barton Key, who had been carrying on an affair with Sickles’s wife. The public sided from the outset with the murderer, especially when his wife’s confession of the romance leaked to the papers. Sickles pleaded not guilty by reason of temporary insanity—a first in American jurisprudence—and was acquitted. Asked later if he meant to kill Key, however, Sickles reportedly replied, “Of course I intended to kill him. He deserved it.”