The definitions of legal insanity differ from state to state, but generally a person is considered insane and is not responsible for criminal conduct if, at the time of the offense, as a result of a severe mental disease or defect, he was unable to appreciate the nature and quality or the wrongfulness of his acts.
The standard for claiming a defendant is not guilty by reason of insanity has changed through the years from strict guidelines to a more lenient interpretation, and back to where it is today, a more strict standard.
Listed below are some of the high-profile cases where defendants used legal insanity as their defense. In some cases the juries agreed, but more often the criminals were found sane enough to know that what they were doing was wrong.
In Aug. 2007, John Evander Couey, the man convicted of kidnapping, raping and burying nine-year-old Jessica Lunsford alive, was declared sane enough to be executed. Couey's attorneys argued that he suffered lifelong mental abuse and had an IQ below 70. The judge in the case ruled that the most credible exam rated Couey's IQ at 78, above the level considered retarded in Florida.
The Jessica Lunsford Case
2. Andrea Yates
In 2002 Andrea Yates was convicted of capital murder for killing three of her five children. In 2006 the conviction was overturned on appeal and she was retried and found not guilty of murder by reason of insanity. Yates had a medical history of displaying psychotic behavior after giving birth.
3. Mary Winkler
Mary Winkler, 32, was charged with first-degree murder for the shotgun shooting death of her husband, Matthew Winkler. A jury convicted Winkler of voluntary manslaughter after hearing testimony that she was physically and mentally abused by her husband. She was sentenced to 210 days and was free after 67 days, most of which was served in a mental facility.
The Trial of Mary Winkler
Anthony Sowell is a registered sex offender who is accused of killing 11 women and keeping their decomposing bodies in his home. In Dec. 2009, Sowell pleaded not guilty to all 85 counts in his indictment. The charges against Sowell, 56, ranged from murder, rape, assault and corpse abuse. However, Cuyahoga County Prosecutor Richard Bombik said there was no evidence that Sowell is insane.
The Crimes of Anthony Sowell
Lisa Montgomery tried to use mental illness when she was being tried for strangling eight-month pregnant Bobbie Jo Stinnett to death and cutting the unborn child from her womb.
Her lawyers said she was suffering from pseudocyesis, which causes a woman to falsely believe she is pregnant and exhibit outward signs of pregnancy. But the jury didn't buy it after seeing evidence of the methodical plan Montgomery used to lure Stinnett into her deadly trap. Montgomery was found guilty and sentenced to death.
The Murder of Bobbie Jo Stinnett
6. Ted Bundy
Ted Bundy was attractive, smart, and had a future in politics. He was also one of the most prolific serial killers in U.S. history. When he was being tried for the murder of one of his many victims, Kimberly Leach, he and his attorney's decided on an insanity plea, the only defense possible with the amount of evidence the state had against him. It did not work and on January 24, 1989, Bundy was electrocuted by the state of Florida.