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.

  • Alabama

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: None
  • Alaska

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for recreational and medical use
    • Impaired Driving: None
  • Arizona

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: Zero tolerance for THC and metabolites
  • Arkansas

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: None
  • California

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical and recreational use
    • Impaired Driving: None
  • Colorado

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Reasonable inference law with legal limit >0 for THC

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for recreational and medical use
    • Impaired Driving: Reasonable inference for THC (5 ng)
  • Connecticut

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical use
    • Impaired Driving: None
  • Delaware

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical use
    • Impaired Driving: Zero tolerance for THC and metabolites
  • District of Columbia

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for recreational and medical use
    • Impaired Driving: None
  • Florida

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: None
  • Georgia

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: Zero tolerance for THC and metabolites
  • Hawaii

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: None
  • Idaho

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: None
  • Illinois

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical use
    • Impaired Driving: Zero tolerance for THC and metabolites
  • Indiana

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: Zero tolerance for THC and metabolites
  • Iowa

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: Zero tolerance for THC
  • Kansas

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: None
  • Kentucky

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: None
  • Louisiana

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: None
  • Maine

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical and recreational use
    • Impaired Driving: None
  • Maryland

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical use
    • Impaired Driving: None
  • Massachusetts

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical and recreational use
    • Impaired Driving: None
  • Michigan

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: Zero tolerance for THC
  • Minnesota

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical use
    • Impaired Driving: None
  • Mississippi

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized
    • Impaired Driving: None
  • Missouri

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized
    • Impaired Driving: None
  • Montana

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Per se >0 for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: THC per se (5 ng)
  • Nebraska

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized
    • Impaired Driving: None
  • Nevada

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Per se >0 for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical and recreational use
    • Impaired Driving: THC per se (2 ng)
  • New Hampshire

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: None
  • New Jersey

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: None
  • New Mexico

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: None
  • New York

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical use
    • Impaired Driving: None
  • North Carolina

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized
    • Impaired Driving: None
  • North Dakota

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: None
  • Ohio

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Per se >0 for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical use
    • Impaired Driving: THC per se (2 ng)
  • Oklahoma

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: Zero tolerance for THC and metabolites
  • Oregon

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for recreational and medical use
    • Impaired Driving: None
  • Pennsylvania

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: THC per se (1 ng)
  • Rhode Island

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical use
    • Impaired Driving: Zero tolerance for THC and metabolites
  • South Carolina

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: None
  • South Dakota

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: Zero tolerance for THC and metabolites
  • Tennessee

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: None
  • Texas

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: None
  • Utah

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: Zero tolerance for THC and metabolites
  • Vermont

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for medical use
    • Impaired Driving: None
  • Virginia

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Per se >0 for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: None
  • Washington

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Per se >0 for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Decriminalized and legal for recreational and medical use
    • Impaired Driving: THC per se (5 ng)
  • West Virginia

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Legal for medical use
    • Impaired Driving: None
  • Wisconsin

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • Zero tolerance for some drugs

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: Zero tolerance for THC
  • Wyoming

    DUID Zero Tolerance or Per se Laws for Some Drugs

    • None

    Marijuana-Specific Laws

    • Possession and Use: Illegal
    • Impaired Driving: None