This plea rarely works. And yet, some of the most famous mass murderers have attempted it

Just this month, Eddie Ray Routh, the killer of ‘American Sniper,' Chris Kyle, was deemed sane by the jury

despite his insanity plea, and convicted of murder. So why is it so hard to prove insanity?

First of all, pleading insanity means that you admit to the crime itself

but you’re not responsible — because you’re insane

Also, you should not be put in prison or sentenced to death

The problem is, that it’s hard to prove insanity. In most US courts, the burden of proof is on the accused

A defendant must prove beyond a reasonable doubt

that he or she was so mentally ill, they didn’t know right from wrong during the crime

In the Routh case, during the closing argument, the prosecution highlighted the fact that Routh did have enough mental capacity after the murder to order a burrito at a fast food restaurant.

If he was insane, according to the prosecution, this food-trip would be unlikely

Another reason the insanity plea usually doesn’t work, according to several lawyers

is that jurors are hesitant to acquit people who have committed horrible crimes

The insanity plea, at its basic level, is a plea of innocence

People often feel that someone who is aware that they committed murder deserves to be convicted, and that the insanity plea is an “easy way out"

Routh confessed to committing murder, yet pleaded insanity

Despite a history of schizophrenia and PTSD, the jury convicted him. Similarly, in May 2014

David Tarloff also tried the insanity plea, after he brutally killed his psychologist. He, too, suffered from schizophrenia

necessitating several hospital stays. But again, the jury found him sane and guilty

A 1995 report from “The American Academy of Psychiatry and the Law” says that

on average, insanity pleas are raised in less than 1% of criminal trials

And only about a quarter of those pleas are successful

Often, the media frenzies over famous murderers who plead insanity - like Ted Bundy

And that creates a false idea that insanity pleas are common, and that they work

Many criminals do have severe mental health issues, and there are many ways of criminally processing them

But for the majority of cases, in the United States, the insanity plea doesn’t work out

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