Is it legal to touch your smartphone while driving if you're using it as a navigation device, not to text or make calls?

Perhaps surprisingly, given Oregon's hands-free law, the answer is yes. But that's not without controversy.

Until last year, many Oregon police officers treated all cellphone use equally when it came to the state's cellphone law, which made it a traffic violation to use a "mobile communications device" while operating a vehicle.

Because part of the law defines an allowable hands-free device as one that allows the driver "maintain both hands on the steering wheel," the law was widely interpreted to mean, "No touching."

"With those definitions in mind the violation of the hands-free cell phone law is pretty simple," said Officer Mike Rowe, a Beaverton Police Department spokesman. "Using a hand to operate a mobile communication device would be a violation of the law as it is written."

But an Oregon Court of Appeals ruling last year upended that argument. The court found that the law only prohibits using a mobile communication device "receive and transmit voice or text communication."

The case, Oregon v. Rabanales-Ramos, centered around a woman charged with driving under the influence of intoxicants after being pulled over for using her cell phone.

An Oregon State Police trooper spotted the telltale glow of a smartphone screen and pulled the woman over. The trooper, according to his testimony, went on to smell the odor of alcohol and notice the driver's slurred speech and glassy eyes.

The Oregon Court of Appeals found the trooper didn't have probable cause to make the stop and suppressed the evidence gathered. Though he saw she was using a smartphone, he couldn't show she had used it receive and transmit voice or text communication.

The court went on to suppress the evidence from the stop.

The Oregon Department of Justice argued the state's case, but spokeswoman Kristina Edmunson said it wouldn't appeal to the Oregon Supreme Court.

That doesn't mean drivers setting up their navigation software, playing music or playing Angry Birds are off the hook.

The 2010 law made drivers' cellphone use a primary offense, meaning that was all it took to initiate a traffic stop. But police can still pull over drivers for the offenses that often result from cellphone use -- reckless driving, for example, or weaving in traffic lanes.

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Have a commuting question? Contact Elliot Njus at enjus@oregonian.com or on Twitter @enjus