The 13 most significant insanity defense cases [SLIDESHOW]

In the wake of Jared Lee Loughner’s attempted assassination of U.S. Rep. Gabrielle Giffords, experts believe that Loughner’s attorneys will seek an acquittal for their client by reason of insanity.

In what will be an incredibly high profile case with 24/7 media coverage, the insanity defense is poised to yet again receive harsh public criticism.  If used, the Arizona shooting trial could rival the most infamous insanity-defense case to date: the Hinckley verdict.  Then, a majority of Americans polled after the verdict felt that the courts had let a guilty man off the hook, and the public outrage spurred Congress to pass the Insanity Defense Reform Act, tightening federal standards of proof.

While this case defined the insanity plea going forward, there are many other notorious cases. Here, we summarize the most significant cases from the insanity defense’s origins in 1843 to how it has evolved in the post-Hinckley era:

Click an image below for larger version.
  • Daniel M'Naghten: acquitted 1843 -- The M’Naghten rule, which was based on the trial and aftermath of the Scottish woodworker’s assassination of a British civil servant, is the basis for American laws on an insanity defense. Commonly known as the “right-wrong” test, the rule says that defendants may be acquitted only if they lack reason and capability of distinguishing right from wrong. During M’Naghten’s trial, psychiatrists testified that he was delusional and the jury agreed, declaring him not guilty by reason of insanity. When the verdict provoked an outcry in England, the House of Lords asked a panel of judges to set down guidance for juries in considering cases where a defendant pleads insanity, and in doing so set precedent for insanity pleas in the future.
  • Richard Lawrence: acquitted, 1835 -- The first person charged with the attempted assassination of a U.S. president was acquitted by reason of insanity after it was clear he believed President Andrew Jackson had not only killed his father, but that the President had conspired to prevent him from returning to his rightful seat on the throne of England and the fortune that awaited him there.
  • Daniel Sickles: acquitted, 1859 -- Congressman Daniel Sickles was charged with murder after he shot and killed U.S. District Attorney Phillip Barton Key, son of Francis Scott Key, in broad daylight in front of the White House. At the time, Key was having a very public affair with Sickle's wife and, during the trial, Sickle's lawyerargued that his client committed the murder in a state of temporary insanity, brought on by the insane jealousy that Key was sleeping with his wife. The jury accepted this argument and he was acquitted.
  • John Schrank: institutionalized for life, 1912 -- While Teddy Roosevelt was campaigning for his second term in Milwaukee, Schrank shot the President at close range, lodging the bullet 3 inches inside his chest (he went on to give the speech he was scheduled to deliver, and died with the bullet still in his chest years later). Schrank was arrested and, during the trial, said that William McKinley had appeared to him in a dream and told him to kill Roosevelt. As a result, the jury deemed he was insane and sentenced him to an asylum.
  • Ezra Pound: declared incompetent, 1946 -- American poet Ezra Pound avoided being tried for treason when he was found incompetent to stand trial. In 1924, he moved to Italy and became involved in Fascist politics, not returning to the U.S. until 1945, when he was arrested on charges of treason for broadcasting Fascist propaganda by radio to the United States during World War II (he once referred to President Roosevelt as "that Jew in the White House”). In 1946, he was acquitted, though declared mentally ill and committed to St. Elizabeths Hospital in Washington, D.C.
  • David Berkowitz: pled guilty, 1978 -- New York's "Son of Sam" murderer claimed he received his killing orders from a neighbor's dog. A psychiatrist found him to be paranoid and delusional, yet the court deemed him fit to stand trial. Rather than follow his attorney's advice and plea insanity defense, Berkowitz pled guilty to the murders of six people and was sentenced to 365 years in prison without parole.
  • John Wayne Gacy: convicted, 1980 -- Gacy admitted the killings, but pled insanity. The jury rejected the plea, and Gacy was convicted and sentenced to death. He was executed in 1994.
After getting a divorce in1976, Gacy took a job as “Pogo the Clown” and as as secretary treasurer in the street lighting commission. Suspicion arose, however, when boys who worked for him started disappearing. When he was brought in for questioning, Gacy denied any knowledge or involvement of their whereabouts, but when the police obtained a search warrant, the truth surfaced. Authorities found 30 skeletons – once high school students and male prostitutes whom he’d lured to his home to rape and torture -- in a crawl space beneath Gacy's home. Gacy pled insanity, which was rejected by the jury, and was convicted and sentenced to death. He was executed in 1994.
  • Kenneth Bianchi, "The Hillside Strangler": pled guilty, 1983 -- Bianchi and his cousin, Angelo Buono, were convicted of raping and killing 10 girls and women during a four-month period from late 1977 to early 1978 in the hills above Los Angeles. Bianchi had fled to Washington before he was charged and taken into custody. There, he attempted to plea an insanity defense, claiming he had a multiple-personality disorder and that one of his alter-egos had committed the crimes. When a forensic psychiatrist determined that Bianchi was fabricating his mental illness, Bianchi pled guilty and agreed to testify against his cousin in exchange for avoiding the death penalty in the Los Angeles case. He is now serving a life sentence in Washington – his cousin died in prison.
  • Jeffrey Dahmer: convicted, 1992 -- Dahmer was arrested in Milwaukee in 1991 after he had killed at least 13, and it was discovered that in his apartment he kept the remains of many young men whom he had brutally murdered, then poured acid on and cut into pieces, preserving their heads and genitals. While on trial, his attorneys attempted to plead Dahmer not guilty by reason of insanity, but failed when prosecutors were able to prove that Dahmer knew full well what crime he was committing, and so the insanity plea was not accepted.
  • John du Pont: convicted, 1997 -- "The wealthiest murder defendant in the history of the United States," was found guilty but mentally ill in his trial for the 1996 murder of Olympic wrestler David Schultz, whom du Pont had shot in front of Schultz's wife.  During the trial, experts brought in by the defense testified that he was a paranoid schizophrenic who thought Schultz was part of an international conspiracy to kill him. Despite his plea of "not guilty by reason of insanity," du Pont was convicted of murder in the third degree but mentally ill -- as a result, he was was sentenced to 13 to 30 years of incarceration while he received psychiatric treatment. He recently died at the Laurel Highland State Correctional Facility. He was 72.
  • Ed Gein: pled guilty, 1968 -- The inspiration for fictional characters in movies such as ‘Psycho,’ ‘The Texas Chainsaw Massacre,’ ‘The Silence of the Lambs,’ Gein robbed graves for bodies needed to perform experiments including necrophilia and cannibalism, which fulfilled his obsessive fantasies. Gein would then construct items and what he thought were keepsakes out of the skin and bones. When his needs escalated to desiring fresher bodies, he murdered two women, which when taken into custody he admitted to. Though initially deemed unfit to stand trial, he was later tried for the two murders after 10 years of confinement in a mental health facility and was sentenced to life imprisonment.
  • Andrew Goldstein: convicted, 2000 -- Goldstein was the paranoid schizophrenic who had been released from a psychiatric hospital just weeks before he tossed Kendra Webdale to a terrifying death under a NYC subway train in January, 1999. His first trial was a mistrial, and at the second trial was sentenced to 25 years to life in prison. During both trials, his defense lawyers argued that Webdale died because the state's mental health system failed Goldstein, but in 2000 a judge said that Goldstein was "too dangerous" to be free.