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of a Portland man, saying he should have been allowed to argue to a jury that he was "sleep driving" at the time and not responsible for driving with a blood alcohol content of nearly twice the legal limit.

The 6-0 ruling is sending shock waves throughout the state's courthouses -- because the high court made clear that prosecutors must prove that a defendant charged with driving under the influence of intoxicants "voluntarily" got behind the wheel.

Read the ruling

For decades, Oregon judges have required prosecutors to prove only that defendants are violating the DUII law by driving with a blood alcohol content of .08 percent or greater -- or that drugs or alcohol impaired their driving abilities regardless of their blood alcohol content.

The new standard could open the floodgates for new defenses: Some drivers will surely argue that they have sleep disorders like James Robert Newman in the case reviewed by the Supreme Court. But others could argue that they were so drunk or high that they lost all ability to make conscious decisions -- and they weren't at fault for driving under the influence.

The decision also could give new hope to leagues of other defendants who claim they didn't know they had consumed booze -- like a man who contended he didn't know his coffee was spiked -- and people who have taken prescription drugs such as Ambien -- like a Eugene man who twice in a nine-day span woke up with DUII citations in his pants pockets and no memory of driving the previous night. They have repeatedly been convicted of impaired driving, despite arguments they didn't act voluntarily.

Prosecutors bemoaned the ruling, saying it's a big hit to efforts to stamp out intoxicated driving. The

is considering rushing to the Legislature before it ends its current session to ask lawmakers to clarify that involuntary driving shouldn't be allowed as a defense to DUII.

But even if a defendant is allowed to argue he or she wasn't consciously driving, "a judge or jury would still have to believe it," said Deena Ryerson, traffic safety resource prosecutor for the state Justice Department.

Defense attorneys celebrated the ruling.

"I just think it's great that the Supreme Court recognized a person has to have some conscious awareness before they can be convicted of a crime and sent to prison," said Robert Thuemmel, who represented Newman in a 2009 trial.

Newman, a 51-year-old Northwest Portland man, contended that he walked from his apartment to a restaurant to drink with friends in 2008, according to a court summary of his case.

A friend gave him a ride back home, and at some point in the night, Newman claimed, he got into his car and started driving while asleep. A Portland police officer said he spotted Newman's car running a red light and straddling the lane lines. The officer activated his overhead lights, and Newman pulled over.

Newman admitted to being drunk, and his blood alcohol content was measured at .15 percent.

But key to Newman's case: He didn't admit to voluntarily or consciously driving. As his Multnomah County Circuit Court trial approached, he argued that he should be allowed to present evidence that he had a history of sleep walking around his apartment. He also was preparing to call a doctor, Joshua Ramseyer, who planned to tell a jury that sleep driving -- similar to sleep walking -- was an unconscious behavior.

"Just as someone's capable of sort of walking around the house, doing goal-directed behavior, such as eating, people can get behind the wheel, start up the car and drive," Ramseyer is quoted as saying in the Supreme Court's written opinion.

But Multnomah County Circuit Judge Marshall Amiton wouldn't allow Newman to present the sleep walking evidence, saying Oregon's DUII law doesn't require the prosecution to prove Newman voluntarily drove.

Newman waived a jury trial, and the judge found him guilty of DUII. It was a felony because he'd been convicted of DUII twice before in the previous decade.

In making its ruling that Newman should get a new trial, the Supreme Court pointed to a general criminal statute, ORS 161.095. It says defendants must commit a "voluntary act" to be held responsible for a crime.

-- Aimee Green