By Jonathan Stempel
WASHINGTON (Reuters) - A divided U.S. Supreme Court on Monday refused to hear an appeal over whether criminal defendants have a constitutional right to assert an insanity defense, leaving in place a paranoid schizophrenic's guilty plea over two murders.
With three of its nine justices dissenting, the court without explanation declined to take up the case of John Joseph Delling, who had been sentenced to life in prison in Idaho over the 2007 shooting deaths of David Boss, a childhood friend, and Brad Morse, whom he had met playing online video games.
According to court papers, Delling said following his arrest that people were involved in wiping his brain when he was 20 years old, and that he had to kill them before turning age 25 to get his soul back.
Lawyers for Delling claimed he was deluded into believing the shootings were in self-defense, but pleaded guilty after being denied the right to assert mental illness.
Three justices - Ruth Bader Ginsburg, Stephen Breyer and Sonia Sotomayor - would have considered Delling's appeal.
"The law has long recognized that criminal punishment is not appropriate for those who, by reason of insanity, cannot tell right from wrong," Breyer wrote for the dissenting justices.
He said Idaho's standard "permits the conviction of an individual who knew what he was doing, but had no capacity to understand that it was wrong."
Idaho, Kansas, Montana, Nevada and Utah have since 1979 passed laws abolishing the insanity defense, though Nevada's supreme court later revived the defense in that state.
The idea of a ban gained some adherents after the acquittal of John Hinckley Jr by reason of insanity over his 1981 assassination attempt on President Ronald Reagan.
In their appeal, Delling's lawyers said the Idaho law violated Delling's protection against cruel and unusual punishment under the 8th Amendment to the U.S. Constitution.
Idaho countered that states are not required to provide any insanity defense, even if a defendant alleges a "moral incapacity" to commit a crime.
It also said that Delling has been under the care of a psychiatrist during his entire incarceration.
The case is Delling v. Idaho, U.S. Supreme Court, No. 11-1515.
(Reporting by Jonathan Stempel; Editing by Howard Goller and Jackie Frank)