Oregon Public Broadcasting

A Clackamas County man accused of killing his stepson last summer, has won a partial victory in his appeal to the Oregon Supreme Court.

As Kristian Foden-Vencil reports, the case gets to the heart of what the state is allowed to ask people who claim mental impairment as a reason for committing a crime.

On a Saturday night in  August of 2008, police were called to the home of Steven Petersen and his family in Happy Valley.

Investigators found the body of his stepson 34-year-old Michael Chapman. He'd been stabbed multiple times.  Petersen was charged with murder.

In pre-trial hearings, Petersen claimed he'd suffered an extreme emotional disturbance on the night of the killing. His attorney, Laura Graser, says he'd been looking after his sick family for a decade.

Laura Graser: "His argument essentially is that the stress of having an extremely physically ill wife and an extremely mentally ill step son for 10 years. He was extremely emotionally disturbed by that and basically just snapped."

Clackamas County Court ordered Petersen to undergo a psychiatric exam. It also required he answer all questions concerning his thoughts and acts at the time of the killing. 

Petersen's lawyer appealed, saying that would violate her client's right against self-incrimination. Lawyers for the state say Petersen waived that right when he testified to his own mental health experts.

The Clackamas County judge found that if Petersen didn't submit to an interview with a state expert, then he couldn't claim emotional disturbance.

His attorney, Laura Graser, appealed to the Oregon Supreme Court.

Laura Graser: "It's a clear established law that they can't ask him about what he did. But the state was saying that although they couldn't ask him what they were doing they could ask him about what he was thinking and feeling. And the defense said no, they couldn't ask him about that either. And essentially, we won the point, although the court turned it around slightly to say the psychiatrist can ask whatever he wants, but the defendent can remain silent or refuse to answer without any penalty whatsoever."

The question is, does that   invalidate the mental examination process? At the state attorney general's office, spokesman Tony Green, says no.

Tony Green: "If the defendant in a future case declines to answer questions, and the court agrees that the defendant should answer these questions, because they are not self-incriminating. Then we have the option of asking the court to strike motions to prevent these type of mental defenses. So we have a remedy in the future if a defendant declines to answer any sort of questions."

Petersen's trail was scheduled for next week, but has been postponed.