Drug Impaired Driving

Every state has laws dealing with alcohol-impaired driving and drug-impaired driving. But unlike the laws for drunk driving, those that address drugged driving are nuanced, difficult to enforce and prosecute and vary substantially by state.

In addition to general impairment laws, there are two basic laws that states tend to use when addressing drug-impaired driving:

  • Zero Tolerance laws make it illegal to drive with any measurable amount of specified drugs in the body. These laws are best suited for illegal drugs: if it is illegal to possess or use a drug, then it is reasonable to prohibit driving after the drug has been possessed and used.
    • 16 states have zero tolerance laws in effect for one or more drugs.
  • Per Se laws make it illegal to drive with amounts of specified drugs in the body that exceed set limits.
    • 6 states have per se laws in effect for one or more drugs.

Marijuana Drug-Impaired Driving Laws

18 states have zero tolerance or non-zero per se laws for marijuana.

  • 9 states have zero tolerance for THC or a metabolite.
  • 3 states have zero tolerance for THC but no restriction on metabolites.
  • 5 states have specific per se limits for THC
  • 1 state (Colorado) has a reasonable inference law for THC

NOTE: GHSA does not compile any additional data on drug impaired driving laws other than what is presented here. For more information, consult the appropriate State Highway Safety Office.

Sources: State Highway Safety Offices.

Short Term Description
Every state has laws dealing with alcohol-impaired driving and drug-impaired driving. But unlike the laws for drunk driving, those that address drugged driving are nuanced, difficult to enforce and prosecute and vary substantially by state.

Responsibility.org Drugged Driving Grant Results: Texas

The Texas Department of Transportation's Traffic Safety Section was one of the recipients of GHSA and Responsibility.org's 2016 grants aimed at combating drug-impaired driving.

After experiencing a 19% increase in fatal crashes involving a drug-impaired driver between 2013 and 2014, TxDOT sought to add more law enforcement officers trained in Advanced Roadside Impaired Driving Enforcement (ARIDE) to their roads.

Trouble Ahead: A Third Of Teens Think It's Legal To Drive Under The Influence Of Marijuana.

A new study commissioned by SADD looks at teens' opinions of marijuana-impaired driving. This article references GHSA and Responsibility.org's 2017 drugged driving report, quoting report author Dr. Jim Hedlund.

Trouble Ahead: A Third Of Teens Think It's Legal To Drive Under The Influence Of Marijuana.

Article by Cheryl Jensen
October 13, 2017

Drugged versus drunk driving: What are police seeing on the roads?

Drugged and drunk driving are both serious issues on our roadways, as GHSA and Responsibility.org's 2017 DUID report showed. Referencing the report, this article details what law enforcement are seeing with regards to both issues in upstate New York.

Drugged versus drunk driving: What are police seeing on the roads?

Article by Anthony Borrelli
August 24, 2017

Marijuana tied to more Colorado collisions but not fatalities, pair of studies says

While recent research by IIHS saw a link between legalized recreational marijuana and increased crash claims, a separate study observed no significant change in traffic fatalities in states with legalized marijuana. GHSA's Kara Macek discusses the challenges of drugged driving research.

Marijuana tied to more Colorado collisions but not fatalities, pair of studies says

June 26, 2017
Article by Jack Queen

Subscribe to Drug Impaired Driving