The U.S. Supreme Court will weigh whether a Kansas man has the constitutional right to pursue an insanity defense, which is not allowed in the Sunflower State, according to The Associated Press.

Attorneys for James Kraig Kahler, who fatally shot his estranged wife and his two teenage daughters along with his grandmother-in-law in 2009, have argued his depression at the time was so severe he broke with reality, according to the AP.

{mosads}The Supreme Court has previously allowed Kansas and four other states to abolish the insanity defense. In his appeal, Kahler’s lawyers will argue before the high court that denying the defense abridges due process, according to the news service.

“Maybe they will establish some ground rules,” Jeffrey Jackson, a law professor at Washburn University in Topeka, told the AP. “They’ve been vague about what the standard is, and maybe now they’re going to tell us.”

Kansas previously allowed a defense based on English law allowing the insanity defense in cases where a defendant is impaired past the point of recognizing their conduct as criminal. Since 1996, however, the state is one of a handful with a stricter law that only allows defendants to cite “mental disease or defect” as a partial defense and requires proof the defendant did not mean to commit the specific crime.

“John Hinckley intended to kill President Reagan. He would not have had a defense in Kansas,” Christopher Slobogin, a professor of both law and psychiatry at the Vanderbilt University, told the AP. “Name an insanity case, the person would not have had a defense in Kansas.”

Slobogin argued such state laws, which are also on the books in Alaska, Idaho, Montana and Utah, bars the defense for virtually any crime committed as a result of delusions.

“Scholars and practitioners have struggled for literally hundreds of years to decide to how to handle evidence of a criminal defendant’s mental condition,” Kansas Attorney General Derek Schmidt told the AP. “Kansas is merely continuing the long tradition of trying different approaches.”