A new law is targeting drivers who have trace amounts of illegal drugs in their systems.
Critics say it could prosecute people who have haven't done anything wrong in Oklahoma.
Twenty states and the District of Columbia have legalized marijuana in some form.
The laws range from medical purposes only to allowing the possession of small amounts for recreational use.
But marijuana remains illegal in Oklahoma.
A law that went into effect Oct. 1 in Oklahoma is aimed at drivers who have trace amounts of marijuana in their system.
The zero-tolerance law would give drivers a DUI if they have reportable amounts of any Schedule 1 drug.
Besides marijuana, Schedule 1 drugs include heroin, LSD, Ecstasy and bath salts.
"The intent is a noble one if we, obviously, want to keep people off the roads that are intoxicated, that's noble," criminal defense attorney James Wirth said.
He said the law could punish drivers who legally smoke marijuana in another state then return to Oklahoma and a few weeks later, still have marijuana in their system and get a DUI.
Owasso State Representative David Derby is one of the co-authors of the law. He calls it a no-brainer, saying Oklahomans do not have the right to possess Schedule 1 drugs. He says police must have probable cause to pull you over and the driver would have to fail a field sobriety test before any blood tests could be taken.
Wirth also is worried that some pain medications, like Codeine, metabolize into a Schedule 1 drug and that could lead someone who's using a legal drug to be arrested or unnecessarily detained.
"It's over-reaching and it has the potential for far more false positives where it's not intoxication that's testing positive, than it does people who are actually intoxicated," Wirth said.
Derby said if a person has a prescription for drugs that metabolize and show signs of a Schedule 1 drug they should be excused from prosecution.