17. - What are the rules of the road?
In both Washington and Colorado, if you get pulled over and an officer has enough probable cause to have your blood tested and you have .5 nanograms per-milliliter of active THC in your blood … then you are assumed to be driving under the influence.
However, that isn’t the only way you can get a DUI for marijuana use. An officer can also use the field test to prove you were impaired and get a conviction that way.