PORTLAND, Ore. -- Driver education manuals often include the phrase, "Driving is a privilege, not a right."
When it comes to driving and marijuana, the most important thing to remember is that nothing is changing with DUII laws.
Police say it's simple math: More people using marijuana means more will get behind the wheel high.
The number of marijuana-related DUIIs have increased in Colorado and Washington, where recreational marijuana has been legalized.
But police say if you're driving dangerously or are impaired, it doesn't matter what drug you've taken or how much you've had.
"The standard for marijuana impairment will be like for any other substance," said Oregon State Police Sgt. Evan Sether. He has been all over Oregon in last few months, training more officers to become Drug Recognition Experts, commonly known as a DRE. There are 180 in the state right now, and Sether is working to get the number up to 215.
WHAT HAPPENS DURING A TRAFFIC STOP?
Police say they also look for heavy perfume or air fresheners frequently used to mask a marijuana odor, droopy or bloodshot eyes and a relaxed appearance.
"Typically, marijuana's effect in the body tends to affect short term memory, cognition, attention span, things like that and then some motor skills," Sether said.
If you're pulled over and an officer suspects you're impaired by any substance, they'll start with asking if you will consent to a standard field sobriety test of your vision and balance.
If the officer has probable cause, they will arrest them for DUII. If the person doesn't consent to a field sobriety test they can still be arrested under probable cause, based on the officer's observations.
The person is then taken to a location (usually the police station) for a breath test. If the test comes back clear, the nearest DRE officer is called to determine whether marijuana or other drugs are a factor. If the person consents to an evaluation, the DRE takes a urine sample.
Portland DUII defense attorney MacDaniel Reynolds of the Reynolds Defense Firm says that the problem is, a urine test can detect pot from as far back as 30 days. He sees marijuana DUIIs go to trial more often than any other substance because it's so ambiguous.
HOW DOES OREGON TEST FOR MARIJUANA INTOXICATION?
Unlike Colorado and Washington that have implemented a .05 nanograms of THC in the blood stream, Oregon has not set a THC limit, like .08 BAC for alcohol.
"At the end of the day, it's an officer making a decision," Reynolds explained. "Whether the officer thinks a person is less sharp mentally or physically than they would have been without using marijuana and that's an officer's opinion, they're going to try and make an informed opinion but at the end of the day, it's a human being making an opinion that could really affect someone's life."
Reynolds agrees with medical dispensary owner Susan Rutherford of Nature's Alternative, who says most adults know how alcohol affects them, but weed may be new territory.
"We just tell people, you need to start slow, see how you react, always be mindful of your surroundings and be responsible," Rutherford said.
CAN YOU SMOKE INSIDE A CAR?
Oregon State Police say it's kind of a grey area, and they're waiting on more information from the legislature, but generally no.
They'll treat it just like the open container law for alcohol. You can have it in the car, but you can't smoke because it could affect the driver.