Marijuana DUI Laws by State: THC Limits and Driving Laws in 2026

Marijuana DUI laws vary significantly from state to state. While every state prohibits driving while impaired by marijuana, only a handful use a specific THC concentration as a legal limit.

Most states instead require prosecutors to prove that marijuana impaired a person’s ability to drive. Other states use zero-tolerance or “any amount” laws that can make it illegal to drive with detectable THC or certain marijuana metabolites in the body under specified circumstances.

There is no nationwide marijuana equivalent to the 0.08% blood alcohol concentration standard used for alcohol.

The table below compares marijuana DUI laws in all 50 states and the District of Columbia, including states with THC blood limits, zero-tolerance rules and impairment-based standards.

For broader information on possession, legalization, home cultivation, medical marijuana and sales, visit The Marijuana Herald’s Marijuana Laws by State guide.

Last updated: September 15, 2026

Marijuana DUI Laws in All 50 States

National summaries maintained by the Governors Highway Safety Association show that most states continue to rely on impairment rather than a numerical marijuana limit, while a smaller group use per se, zero-tolerance or any-amount standards. Current statutes are especially important because older national charts can miss changes or exceptions created by legalization.

Which States Have a Specific THC Driving Limit?

Only a small number of states use a specific THC concentration as a per se driving limit.

Washington uses a limit of 5 ng/mL of THC in whole blood when measured within two hours of driving. Illinois also uses a 5 ng/mL whole-blood threshold, along with a 10 ng/mL threshold for other bodily substances. Montana uses a 5 ng/mL blood threshold.

Ohio uses one of the country’s lower THC thresholds, with a limit of 2 ng/mL in whole blood, blood serum or plasma and 10 ng/mL in urine.

Colorado is different. A blood THC concentration of at least 5 ng/mL creates a “permissible inference” that a driver was under the influence. That means the result can be used as evidence of impairment, but it does not automatically establish guilt.

Nevada is another important exception. The state previously had general numerical marijuana limits, but its 2 ng/mL delta-9 THC and 5 ng/mL 11-hydroxy-THC thresholds now apply in specified felony DUI cases rather than serving as a general per se standard for every marijuana DUI.

Is 5 ng/mL of THC the Marijuana Equivalent of a 0.08% Alcohol Limit?

No.

Although several states use 5 ng/mL of THC in some form, there is no nationally accepted THC concentration equivalent to the 0.08% blood alcohol concentration standard.

Alcohol and THC behave differently in the body. Blood alcohol concentration has a comparatively established relationship with alcohol consumption and impairment. THC concentrations can rise quickly after marijuana use and then decline rapidly, and the relationship between a particular THC concentration and a person’s level of impairment is less straightforward.

That is one reason most states have not adopted a universal numerical THC limit.

Federal highway-safety research has also cautioned against treating a particular THC concentration as a direct equivalent to a blood alcohol concentration.

Can You Get a Marijuana DUI With Less Than 5 ng/mL of THC?

Yes.

A THC limit does not necessarily create a safe harbor below that number.

Washington, for example, allows evidence of a THC concentration below 5 ng/mL to be considered along with other evidence when determining whether a person was under the influence of marijuana.

Similarly, states with impairment-based DUI laws do not need a driver to reach any particular THC concentration. A prosecutor may instead rely on the driver’s behavior, observations by law enforcement, performance on field sobriety tests, toxicology results, statements about marijuana consumption and other evidence.

A driver therefore should not assume that being below 5 ng/mL, or any other numerical level, means it is legal to drive.

Which States Have Zero-Tolerance Marijuana DUI Laws?

Several states take an approach that is stricter than a numerical impairment limit.

These laws generally prohibit driving with THC or specified marijuana metabolites in the body, although the exact language and available defenses differ substantially by state.

Indiana, Iowa, Oklahoma, Pennsylvania, Utah and Wisconsin are among states with zero-tolerance or any-amount provisions relevant to marijuana driving. Arizona and Georgia also have broad drug-presence provisions, although Arizona law includes important limitations involving metabolites and protections for registered medical marijuana patients.

These statutes should not all be treated as identical. Some apply to active THC, some include metabolites, some contain medical-use defenses or exceptions, and others operate alongside separate impairment-based DUI laws.

Pennsylvania, for example, prohibits driving with any amount of a Schedule I controlled substance or its metabolite in the blood and separately prohibits driving while under the influence of a drug to a degree that impairs safe driving.

Important State-Specific Marijuana DUI Exceptions

Some states have marijuana DUI provisions that do not fit neatly into broad categories such as impairment-based, per se or zero-tolerance laws. Minnesota and South Dakota are two notable examples.

Minnesota Excludes Marijuana From Its Any-Amount Drug Rule

Minnesota law makes it illegal to drive with any amount of certain Schedule I or II controlled substances or their metabolites in the body, but it expressly excludes cannabis flower, cannabis products, hemp-derived products, artificially derived cannabinoids and tetrahydrocannabinols from that provision.

Instead, marijuana DUI cases generally depend on evidence that the driver was under the influence of cannabis. This is important because some older state-by-state DUI charts have classified Minnesota as a marijuana zero-tolerance state.

South Dakota Has a Separate Marijuana Rule for Drivers Under 21

For most adult drivers, South Dakota prohibits driving while under the influence of marijuana rather than imposing a specific THC concentration limit.

Drivers younger than 21 face a separate rule. State law prohibits a person under 21 from driving after consuming marijuana for as long as physical evidence of that consumption remains present in the person’s body.

This means South Dakota generally uses an impairment standard for adult drivers while applying a much stricter marijuana rule to drivers under 21.

Active THC vs. THC Metabolites

Marijuana DUI laws sometimes distinguish between active THC and THC metabolites.

Delta-9 THC is the primary intoxicating cannabinoid in marijuana and is generally what states are referring to when they establish a numerical blood-THC threshold. After THC is processed by the body, it is converted into metabolites, including compounds that may remain detectable after the intoxicating effects have worn off.

That distinction matters because state laws vary. Some laws focus specifically on active delta-9 THC, while others address THC metabolites or other evidence that marijuana was consumed.

A positive test for a THC metabolite therefore does not necessarily mean a person was impaired at the time of driving. The National Highway Traffic Safety Administration notes that THC metabolites can remain detectable for days or weeks after consumption, long after impairment has ended.

How Do Police Prove Marijuana-Impaired Driving Without a THC Limit?

In a state without a numerical THC threshold, the central question is generally whether marijuana affected the driver’s ability to safely operate a vehicle.

Law enforcement and prosecutors may rely on a combination of driving behavior, the circumstances surrounding a traffic stop or crash, physical observations, field sobriety testing, toxicology testing, statements from the driver and testimony from officers or drug-recognition experts.

A positive marijuana test does not necessarily answer when marijuana was consumed or how impaired a particular driver was at the time. The legal significance of a toxicology result therefore depends heavily on the state’s statute and the other evidence in the case.

Does Legal Marijuana Protect You From a DUI?

No.

Legalizing possession or recreational marijuana does not make it legal to drive while impaired.

The same principle applies to medical marijuana patients. A medical marijuana card authorizes marijuana use within the boundaries of a state’s medical program, but it does not authorize impaired driving.

Some states do provide medical patients with protections from an automatic drug-presence violation. Arizona, for example, provides statutory protections related to the presence of marijuana components or metabolites when concentrations are insufficient to cause impairment, while Illinois’ per se THC provision contains an exception relating to lawful medical marijuana use.

A medical authorization therefore may matter under a particular statutory provision, but it is not a defense to actually driving while impaired.

Can You Get a Marijuana DUI the Day After Using Marijuana?

Potentially, but the answer depends on whether the person is impaired and on the law of the state.

There is no nationwide rule establishing that a person can legally drive a specific number of hours after using marijuana.

THC levels and impairment can be affected by the method of consumption, dose, product potency, frequency of use and individual differences. Edible marijuana products can also have a different onset and duration than inhaled marijuana.

In a zero-tolerance or any-amount state, detectable THC or a prohibited metabolite may create additional legal concerns even when a driver does not feel impaired.

The safest legal approach is not to drive while experiencing the effects of marijuana.

Are Marijuana DUI Laws Different for Edibles?

Generally, state DUI laws focus on impairment or THC in the body rather than whether the marijuana was smoked, vaporized or eaten.

A person can therefore receive a marijuana DUI after consuming an edible just as they can after smoking marijuana.

Edibles can create a particular risk because their effects may take longer to begin and may last longer than the effects associated with inhaled marijuana. There is no separate exemption simply because the marijuana was consumed as food or a beverage.

Is It Legal to Have Marijuana in Your Car?

Legal possession and impaired driving are separate issues.

In states where marijuana possession is legal, an adult may generally transport marijuana within applicable possession limits, but vehicle-storage and open-container restrictions may apply.

A person can therefore legally possess marijuana while still violating another law if the product is open, improperly stored or being consumed inside the vehicle.

Possessing marijuana legally also does not provide any protection for driving while impaired.

For state-specific possession rules, see our Marijuana Laws by State guide.

Frequently Asked Questions

What is the legal THC limit for driving?

There is no nationwide legal THC limit for driving. Most states do not use a numerical THC threshold and instead require evidence that marijuana impaired the driver.

Among states with numerical standards, thresholds vary. Wisconsin uses 1 ng/mL of delta-9 THC in blood, Ohio uses 2 ng/mL, and Washington, Illinois and Montana use 5 ng/mL in specified circumstances. Colorado also uses 5 ng/mL, but as a permissible inference of impairment rather than an automatic per se violation.

Which states have a 5 ng/mL THC limit?

Washington, Illinois and Montana use 5 ng/mL of delta-9 THC in blood as part of their marijuana-driving laws. Illinois also establishes a 10 ng/mL threshold for other bodily substances.

Colorado uses 5 ng/mL differently. Reaching that level creates a permissible inference that the driver was under the influence, but does not automatically establish a violation.

Can you get a marijuana DUI if your THC level is below the state’s limit?

Yes. A numerical THC limit does not necessarily create a legal safe harbor below that amount.

Washington, for example, allows a THC concentration below 5 ng/mL to be considered along with other evidence of impairment. States without numerical THC limits may prosecute marijuana DUI cases based entirely on evidence that the driver was impaired.

Can you get a DUI for marijuana even if marijuana is legal?

Yes. Every state prohibits driving while impaired by marijuana regardless of whether marijuana possession is legal for recreational or medical use.

Legalization allows marijuana possession and use under specified circumstances. It does not legalize driving while impaired.

Does a medical marijuana card protect you from a DUI?

No. Medical marijuana patients can still be prosecuted for driving while impaired.

However, medical-marijuana status can matter under certain state laws. Some states provide registered patients with protections or exceptions from particular automatic drug-presence or per se provisions. Those protections do not authorize driving while actually impaired.

Can you get a marijuana DUI without a blood test?

Yes. In states that rely on an impairment standard, police and prosecutors may use driving behavior, physical observations, field sobriety testing, statements, testimony from officers or drug-recognition experts and other evidence.

A blood or other toxicology test can provide additional evidence, but whether one is necessary for a particular charge or conviction depends on state law and the circumstances of the case.

Is a positive THC test enough to prove marijuana impairment?

Not necessarily. THC or marijuana metabolites can remain detectable after use, and the legal significance of a positive result varies by state.

In impairment-based states, prosecutors generally must establish that marijuana affected the person’s ability to drive safely. In per se, any-amount or zero-tolerance-style states, the presence or concentration of THC may have greater independent legal significance.

Is 5 ng/mL of THC the same as a 0.08% alcohol level?

No. There is no scientifically or legally accepted nationwide THC concentration equivalent to a 0.08% blood alcohol concentration.

THC and alcohol behave differently in the body, and a particular blood THC concentration does not correspond as consistently with a particular level of impairment.

About This Guide

Marijuana DUI laws can change through legislation, court decisions and regulatory changes. The Marijuana Herald regularly reviews this guide to reflect changes in state law.

This guide provides a general overview of marijuana driving laws and is not legal advice. DUI statutes are highly fact-specific, and additional rules may apply to drivers younger than 21, commercial drivers, medical marijuana patients, repeat offenders and cases involving crashes or injuries.

For detailed information on marijuana possession, cultivation, medical access, sales and penalties in individual states, visit The Marijuana Herald’s Marijuana Laws by State guide.

Official Sources

This guide was compiled and cross-checked using state statutes, vehicle codes and official or nationally recognized resources tracking marijuana-impaired driving laws, including:

• Governors Highway Safety Association: Drug-Impaired Driving Laws
• Insurance Institute for Highway Safety: Alcohol and Drugs
• National Conference of State Legislatures: State Cannabis Policy Enactment Database
• National Conference of State Legislatures: Traffic Safety Legislation Database
• National Highway Traffic Safety Administration: Drug-Impaired Driving
• Individual state DUI statutes, vehicle codes and other official state government resources where clarification was needed

State laws vary considerably in how they treat THC, marijuana metabolites, blood concentration limits and evidence of impairment. Some states use specific THC thresholds, others prohibit certain detectable amounts, and many rely primarily on evidence that a driver was impaired.

Because marijuana DUI laws can change through legislation, regulations and court rulings, readers should consult the current statute in their state for the most up-to-date requirements.