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21 Gripping Insanity Plea Statistics

In many courts around the world, defendants are typically found guilty or innocent of a crime. There are some variations on these two basic verdicts and how a defendant will plead. In the United States, for example, a defendant may plead guilty by the Alford Doctrine, which allows for no acknowledgment of guilt, but concedes that there is enough evidence to convict. For a variation on the plea of innocence, a defendant may also plead that they are mentally ill.

The idea that mentally ill people should not be held morally responsible for a crime committed dates back to the Roman Empire.

Insanity Plea Facts

In the United States, there are actually 51 different types of insanity defenses allowed because every state and the federal government all have different legal definitions of this defense. Although successful defenses are rare, on average, the plea is also quite rare. Only 0.85% of cases have an insanity plea entered on behalf of a defendant.

  • Over 70% of defendants will withdraw their plea when a state-appointed expert finds that they meet the legal definition of sanity.
  • 60% of the laws in the United States require that the determination of sanity be from a psychologist or a psychiatrist.
  • Only 12% of the laws that allow for an insanity plea require some sort of test in order to determine legal sanity.
  • There are 51 types of insanity defense in the United States.

A lot of the success or failure of an insanity plea right now is determined on the quality of witness testimony and the skill of the examiner. This has two very real consequences that must be considered: people who are very skilled may have the ability to fool an examiner and an incompetent examiner may put someone behind bars when they really shouldn’t be there by the current letter of the law. Remember – the crime itself is not in this debate. It is whether or not someone meets the legal definition of insanity and therefore has a lack of personal responsibility.

Is The Insanity Defense Successful?

  • In a 1991 study across multiple states, it was found that success rates for insanity pleas were about 25%.
  • In the State of Colorado, a 44% success rate was discovered for cases that involved an insanity defense.
  • Those with psychotic, affective, or mental disorders were the most likely to be acquitted because of an insanity defense.
  • Bench trials are more likely to produce a successful insanity defense than jury trials.
  • People who suffer from personality disorders and people charged with sex crimes are the least likely to find success with an insanity plea.
  • The modern insanity plea is built upon 1984 legislation that was passed after the assassination attempt on Ronald Reagan.
  • People who have received 5 or more psychiatric hospitalizations are more likely to receive not guilty by reason of insanity verdict.

The issue of mental health is fast becoming a leading topic of discussion in the United States and around the world. In the US especially, numerous incidents of violence are occurring and many of them seem to stem around the mental health of a person. Although the topic tends to turn toward the validity of the 2nd Amendment, the fact that people are not receiving the treatment they need for their mental health is disturbing. With millions of crimes occurring every year, even less than 1% of insanity pleas being associated with that number means a potential of tens of thousands of people not receiving the treatment they require to be healthy.

What Kind of Crimes Are Committed?

  • 65% of offenses that occur which result in an insanity plea are crimes that occur against other people.
  • The most frequent crime that is defended by an insanity plea is murder, which accounts for 19% of the total please.
  • Felonies account for 94% of all insanity pleas.
  • The primary reason why an insanity plea is entered is because of a substance abuse disorder that the defendant has.
  • Only 5% of insanity pleas originate from an organic mental disorder.
  • Of the defendants that were found guilty despite an insanity plea, 88% of them were found to be clinically sane.
  • When psychiatric results are removed from the equation, the most likely reason why someone will be found not guilty of a crime because of insanity is because of a schizophrenia diagnosis.

For the most part, it appears that justice is typically served in most cases. Although no justice system is perfect, there is the issue that over 10% of defendants who are found guilty despite a not guilty plea because of insanity are still not found to be clinically sane. If the statutes specifically state that by a legal definition, someone who is not clinically sane does not have the ability to reason right from wrong, then justice is not being served. Does it seem like a majority of these pleas are just a way to try to get out of a crime? It does. That still doesn’t make a miscarriage of justice on an individualized basis justifiable.

Is An Insanity Please Just an Excuse?

  • It is more common for a defendant to rely on a state of temporary mental impairment or diminished capacity than to plead insanity.
  • The overall success rate of insanity pleas is about 0.26% and has remained constant for several years.
  • Less than 20% of expert witnesses require additional certifications in order to gauge the sanity of someone successfully by a legal definition.

If the laws could be made a little more consistent from state to state, the ability to adequately know what to expect from an insanity plea would be a bit more predictable. With that being said, what needs to happen first and foremost is an increase in the ability to treat those who have a clinical need. Whether someone knows right from wrong is important, but when violence occurs and a family member is lost because of mental illness, there really is no victory whatsoever.

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