Is There a Marijuana DWI Test?

There is a new test that measures drivers’ saliva for levels of Marijuana and other illicit drugs. The mouth swabs have been used since 2019 by several states, but studies have shown that the tests are not a reliable measure of drug-induced impairment. The marijuana DWI tests take approximately 5 minutes to complete and can identify THC as well as opiates, cocaine, and methamphetamines.

Texas Penal Code § 49.04 states that you can be charged with a DWI if you do not have the normal use of your physical or mental faculties because of marijuana use. While researchers are working on a more precise test for marijuana DWIs, they cannot agree on a universal impairment value– since everyone processes the drug differently. DWI penalties in Texas are generally the same regardless if you were impaired by excess alcohol, prescription medications, or an illegal drug.

It is challenging to prove legal impairment of a driver on Marijuana– given current tests, and several defenses can be raised. If you were arrested for driving while high, speak to a drug possession attorney in Dallas about your rights. Contact Peveto Law Office and request a free consultation regarding your marijuana DWI case.


  1. Fight DUI Charges, Driving While High Charge: What Happens?,
  2. ScienceDaily, New breathalyzer can detect marijuana,