Anthony Sowell pleads insanity - legal tactic rarely works.

Anthony Sowell, the registered sex offender accused of killing 11 women and leaving their remains in and around his Cleveland home, pleaded not guilty by reason of insanity Thursday to 85 counts on his indictment.

Yet the ruling of "not guilty by reason of insanity" is almost never heard in courtrooms because juries are too skeptical, say legal experts. Jeffrey Dahmer, "Son of Sam," and Jack Ruby all tried this defense and failed.

"Even with the supportive testimonies of expert psychiatrists, jurors don't like to buy this idea because they feel like they are letting someone skirt responsibility," says Robert Pugsley, professor of law at Southwestern Law School in Los Angeles. [Editor's note: The original version misstated the institute's name].

Mr. Sowell was indicted on charges that include murder, rape, assault, and corpse abuse. He is accused of murdering 11 women and attacking three others. He could get the death penalty if convicted of any of the killings.

What Sowell's attorneys must prove

Mr. Pugsley and other analysts say they will be watching the Sowell trial to see whether or not it advances the McNaughton rule – the legal code that offers guidance on insanity pleas.

The rule is twofold, Pugsley says.

1. Did he understand the nature of his act?

2. Did he know the act was morally wrong?

"He will fail miserably on both accounts," Assistant Cuyahoga County Prosecutor Richard Bombik said outside court.

Prosecutors in this case will argue that there was a pattern of the accused apparently preying on "easy victims" – those who are more vulnerable because they are homeless or living alone and dealing with drug and alcohol addictions – and Sowell knew what he was doing, says Jessica Levinson, an adjunct professor at Loyola Law School.

She says that, under Ohio law, a person can be mentally ill, but still know that a specific act is wrong.

"In that event, that person will not be deemed legally insane," says Professor Levinson. "It will be very difficult to prove that Sowell didn't know rape and murder are wrong."

Psychiatric confinement possible

Both Pugsley and Levinson point that, if found guilty, Sowell will likely be committed to a psychiatric hospital where he will be examined for somewhere between 45 days to six months and then be assigned to indefinite commitment if found a danger to himself or society.

"It's possible that a person could spend years inside a psychiatric institution, beyond the years given as punishment for the crime itself," says Pugsley.

Cuyahoga County Prosecutor Bombik he was confident Sowell would be ruled competent to stand trial.

When Sowell's defense team is settled, psychiatric testing is likely. The issue will be handled by the trial judge beginning with a pretrial hearing Monday.

"While there are different standards used in the states, by any standard proving legal insanity is an upward battle," says Levinson.

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