Irresistible impulse

In criminal law, irresistible impulse is a defense by excuse, in this case some sort of insanity, in which the defendant argues that they should not be held criminally liable for their actions that broke the law, because they could not control those actions.

In 1994, Lorena Bobbitt was found not guilty when her defense argued that an irresistible impulse led her to cut off her husband's penis.

The Penal Code of the U.S. state of California states (2002), "The defense of diminished capacity is hereby abolished ... there shall be no defense of ... diminished responsibility or irresistible impulse..."

Irresistible impulse in English Law
In English Law the concept of "irresistible impulse" was developed in the 1960 case R v. Byrne. The appellant (described as a violent sexual psychopath) strangled then mutilated a young girl, it was alleged that Byrne suffered from violent and perverted sexual desires which he found impossible to control. Lord Parker C.J. broadened the definition of "abnormality of mind" to include those lacking 'the ability to exercise will-power to control acts in accordance with [their] rational judgment".

"Irresistible impulse" can be pleaded only under the defense of diminished responsibility not under the defense of insanity. Thus it operates only as a defense to murder, reducing the charge to manslaughter, giving the judge discretion as to length of sentence and whether committal would be more appropriate than incarceration.

Irresistible impulse in the media

 * The novel and subsequent movie Anatomy of a Murder centered on a court case in which irresistible impulse was used to justify a husband murdering the man who raped his wife.


 * The movie Adam's Rib, while not specifically using the term "irresistible impulse," centered on a case in which the defendant described to her attorney certain symptoms that strongly suggest a dissociative episode of the type that might produce such an impulse. That said, the defense in that case actually asked for jury nullification rather than a not-guilty-by-reason-of-insanity verdict.