InsanityUS Representative Daniel E. Sickles is the first defendant known to have won an acquittal of a first degree murder charge with a plea of not guilty by reason of temporary insanity.  In 1859 he shot and killed Philip Barton Key, the son of composer Francis Scott Key, in broad daylight in front of many witnesses. Key was unarmed. It was widely known at the time that Key was carrying on an affair with Sickles’ wife. Screaming that Key must die for having “dishonored” his house, Sickles fired two bullets into him. The jury sympathized with Sickles. Key had been his close friend. When it appeared that Key was on the verge of losing his job as US Attorney for the District of Columbia, Sickles used his influence to save Key’s job.  Although there was no doubt that Sickles killed Key, it was felt by many that Key brought about his own demise. The culture of the time saw Sickle as a man wronged who stood up for his honor. The trial lasted twenty days.  The verdict was returned after an hour of deliberation “ œnot guilty by reason of temporary insanity.