‘American Sniper’ Murder Trial: It’s Really Hard to Win With Insanity Plea

February 26, 2015 Updated: February 26, 2015

The former Marine who was convicted in the murder of Chris Kyle, the subject of “American Sniper,” had received psychiatric treatment and took medication for schizophrenia, but this wasn’t enough for jurors.

The jury found that Eddie Ray Routh, who was convicted of murder earlier this week, was sane enough to know right from wrong, which is the legal threshold.

It isn’t enough for a defendant to just have a history of mental illness, as some legal experts have noted.

“It is very difficult to convince a jury that a defendant is legally insane,” says Page Pate, a trial attorney with 20 years’ experience. “The test used in criminal cases varies somewhat from state to state, but generally requires that the person being charged did not know the difference between right and wrong at the time he committed the crime.”

As a result, lawyers rarely try to use the defense.

“That is a very difficult standard to meet. It is not enough to just be mentally ill, even with a diagnosed and accepted condition like PTSD. The mental illness has to be so severe that the person literally does not know what he is doing,” Pate adds.

Routh had a history of mental problems, and even Kyle himself described him as “straight-up nuts.” He talked about human-pig creatures and the apocalypse.

“It is not enough for a defendant to have a history of psychiatric problems,” says Dr. Carole Lieberman, who is a bestselling author and forensic psychiatrist in the department of psychiatry at UCLA. “What is in question is the state of mind of the defendant as they committed the crime. If, despite their mental or psychiatric impairment, they were still able to distinguish right from wrong, and chose to do wrong, then the insanity plea doesn’t exonerate them. In Routh’s case, the evidence showed that he did know that what he did was wrong,”

But in Routh’s case, he confessed to killing Kyle and another man,  apologized to their families, and tried to escape police capture.

Kyle, a former Navy SEAL sniper, volunteered with veterans facing mental health problems after he left the military. The hit film, “American Sniper,” based on his memoir about his four tours in Iraq contributed to intense interest in the case.

The jury in the trial three options: find Routh guilty of capital murder, find him not guilty or find him not guilty by reason of insanity. With the conviction, Routh received an automatic sentence of life in prison without parole. 

The prosecution argued that Routh, 27, was a troubled drug user who knew right from wrong. The claims were apparently enough to convince the jury he wasn’t insane.

Barrett Hutchinson, one of the jurors, told ABC’s “Good Morning America” they were not convinced by the claim that Routh was having a psychotic episode. “He knew the consequences of pulling the trigger,” Hutchinson said.

If the insanity defense worked in Routh’s case, he would have faced up to life in a state mental hospital.

The Associated Press contributed to this report.