Drug Impaired Driving
The chart below describes the statewide laws related to drug-impaired driving across the country. Use the arrows below the chart to toggle through the states in alphabetical order. To advance slowly, click the single right arrow (>). To jump to the end, click the double arrows (>>). Or use the filter by state feature to jump to a specific state.
Scroll down for a summary and overall totals of the number of states that have specific provisions.
Last updated in January 2024. Laws last reviewed by State Highway Safety Offices in March 2024.
| California | Colorado | Connecticut | Delaware |
|---|---|---|---|
| DUID Zero Tolerance or Per se Laws for Some Drugs
None |
DUID Zero Tolerance or Per se Laws for Some Drugs
Permissible inference law >0 for THC |
DUID Zero Tolerance or Per se Laws for Some Drugs
None |
DUID Zero Tolerance or Per se Laws for Some Drugs
Zero tolerance for some drugs |
| Marijuana Possession and Use
Decriminalized and legal for medical and recreational use |
Marijuana Possession and Use
Decriminalized and legal for recreational and medical use |
Marijuana Possession and Use
Decriminalized and legal for medical and recreational use |
Marijuana Possession and Use
Decriminalized and legal for medical use |
| Marijuana Impaired Driving
None |
Marijuana Impaired Driving
Permissible inference for THC (5 ng) |
Marijuana Impaired Driving
None |
Marijuana Impaired Driving
Zero tolerance for THC and metabolites |
None
Decriminalized and legal for medical and recreational use
None
Permissible inference law >0 for THC
Decriminalized and legal for recreational and medical use
Permissible inference for THC (5 ng)
None
Decriminalized and legal for medical and recreational use
None
Zero tolerance for some drugs
Decriminalized and legal for medical use
Zero tolerance for THC and metabolites
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.
- 5 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.
- 10 states have zero tolerance for THC or a metabolite.
- 4 states have zero tolerance for THC but no restriction on metabolites.
- 4 states have specific per se limits for THC
- 1 state (Colorado) has a permissible inference law for THC
NOTE: GHSA does not compile any additional data on drug-impaired driving laws other than what is presented here. A compilation of state marijuana laws is available via the Insurance Institute for Highway Safety, and information on marijuana-impaired driving laws is available from the National Alliance to Stop Impaired Driving. For more information, consult the appropriate State Highway Safety Office (SHSO).
Source: SHSOs.
Last updated in January 2024. Laws last reviewed by SHSOs in March 2024.