How do officers determine marijuana impairment?

If you are pulled over, whether you were speeding, missed a stop light, or showing any other indication of impairment, and the police officer suspects marijuana usage, they will ask you to submit to tests, similar to alcohol related DUIs.

Unlike alcohol DUIs, though, there is not a quick test one can do on the scene that can determine your impairment.

We used to have Implied Consent Warnings for blood. The only way they can test THC was by way of blood warnings, like if they suspected you had marijuana in your system. They no longer draw blood based on blood warnings, though.

Now, the police are getting search warrants.

The police usually run through Implied Consent Warnings for alcohol and include the THC language, but they aren’t going to do a blood draw based on that. They’re going to do it based on a search warrant.  Then of course, you don’t have the option of refusing to have your blood drawn.

If you are stopped and suspected of marijuana only, you can refuse to voluntarily submit to the blood draw and the police officers will need to get a search warrant. Officers can suspect marijuana and say you’ve are impaired. “I smell marijuana on the person,” they might say. Then they call and get a search warrant.