Real-life inspiration (SPOILERS)

"Anatomy of a Murder" is a faithful recreation of an actual 1952 murder case in which the defense attorney was John Voelker, who wrote the original novel under the pen name Robert Traver. The specifics are the same: An army lieutenant, Coleman Peterson, shot a barkeeper, Maurice Chenoweth, whom he accused of raping his beautiful and often flirtatious wife. The lieutenant pleads not guilty by reason of temporary insanity and a psychiatrist testifies that he suffered an "irresistible impulse." The jury acquits him and the couple then skip town in their mobile home without paying the legal bill, with Peterson leaving a note that he'd had an "irresistible impulse" to leave. Google will turn up a number of sites that tell the full story.