Marijuana and Driving in Massachusetts

Last updated: July 2026

Although recreational marijuana is legal in Massachusetts, driving under its influence remains a crime under G.L. c. 90, § 24. There is no legal THC limit—the Commonwealth must prove that marijuana actually impaired your ability to drive. A first offense carries up to a one-year license suspension, fines, and possible jail time.

Massachusetts legalized medical marijuana in 2012 and recreational marijuana in 2016. While adults 21 and older can now legally possess and use marijuana, one thing has not changed: operating a motor vehicle while impaired by marijuana is a criminal offense.

As marijuana use has become more common, so have OUI-drug prosecutions. These cases raise complex legal and scientific questions—and the law governing them has evolved significantly in recent years. This guide explains how Massachusetts treats marijuana-impaired driving, what prosecutors must prove, and what rights you have if your license is at risk.

Is It Illegal to Drive After Using Marijuana in Massachusetts?

Yes. Operating under the influence of marijuana is a crime under G.L. c. 90, § 24—the same statute that governs drunk driving. Legalization of possession did not legalize impaired driving.

The Massachusetts OUI statute, G.L. c. 90, § 24, prohibits operating a motor vehicle while under the influence of intoxicating liquor, marijuana, narcotic drugs, depressants, or stimulant substances. Marijuana is explicitly named in the statute.

A driver does not need to be heavily intoxicated to be convicted. The Commonwealth only needs to prove that the driver’s ability to operate a vehicle safely was diminished by marijuana. It also makes no difference whether the driver uses marijuana recreationally or holds a medical marijuana card—impaired operation is unlawful either way.

Is There a Legal THC Limit for Driving in Massachusetts?

No. Unlike the 0.08% blood alcohol limit for alcohol, Massachusetts has no per se THC limit. Because THC can remain in the body for days or weeks after use, a blood or urine test cannot reliably establish impairment at the time of driving.

This is one of the central challenges in marijuana OUI cases. With alcohol, a breath test provides a measurable blood alcohol concentration that correlates with impairment. Marijuana works differently.

THC, the primary psychoactive compound in marijuana, can remain detectable in a person’s system for days or even weeks after use—long after any impairing effects have worn off. A positive test does not establish that a driver was impaired at the moment they were operating the vehicle. There is also no roadside chemical test comparable to a breathalyzer that reliably measures marijuana impairment.

For chronic or medical users, the analysis is even more complicated, because tolerance can develop and detectable THC may persist without any corresponding impairment.

What Did Commonwealth v. Gerhardt Change About Field Sobriety Tests?

In Commonwealth v. Gerhardt (2017), the Massachusetts Supreme Judicial Court ruled that police cannot testify that a driver “passed” or “failed” field sobriety tests in marijuana cases, because those tests were designed to detect alcohol impairment—not marijuana. Officers may only describe their observations as “roadside assessments.”

Standardized field sobriety tests—the walk-and-turn, the one-leg stand, and the horizontal gaze nystagmus test—were developed and validated to detect alcohol impairment. Their scientific reliability for detecting marijuana impairment has not been established.

Recognizing this, the Supreme Judicial Court set important limits in Commonwealth v. Gerhardt, 477 Mass. 775 (2017). Under Gerhardt:

• Police may not testify that a driver “passed” or “failed” field sobriety tests in a marijuana OUI case
• These procedures must be referred to as “roadside assessments,” not “tests”
• Officers may describe their observations of a driver’s balance, coordination, and mental acuity—skills relevant to safe driving
• Officers may not offer an opinion that the assessments proved the driver was under the influence of marijuana

This decision significantly affects how these cases are prosecuted and defended. The limitations on officer testimony create meaningful opportunities to challenge the Commonwealth’s evidence.

What Must the Prosecution Prove in a Marijuana OUI Case?

To convict, the Commonwealth must prove beyond a reasonable doubt that the defendant operated a motor vehicle, on a public way, while their ability to drive safely was actually impaired by marijuana. Mere recent use is not enough.

As the Supreme Judicial Court explained in Commonwealth v. Daniel, 464 Mass. 746 (2013), the prosecution must establish actual impairment—not just consumption. The essential elements are:

• Operation: The defendant operated a motor vehicle
• Public way: The operation occurred on a public way or a place where the public has access
• Impairment: The defendant’s ability to operate safely was diminished by marijuana at the time of driving

Because there is no reliable chemical measure of marijuana impairment and because officer testimony is limited under Gerhardt, proving the impairment element beyond a reasonable doubt can be difficult for the Commonwealth. Expert medical testimony is often required to connect observed behavior to marijuana use.

What Are the Penalties for a Marijuana OUI in Massachusetts?

Penalties for an OUI-marijuana conviction mirror those for alcohol OUI. A first offense carries a fine of $500–$5,000, up to 2½ years in jail, and a one-year license suspension. Penalties increase substantially for subsequent offenses.

Massachusetts treats OUI-drugs the same as OUI-alcohol under G.L. c. 90, § 24. Penalties escalate with each offense:

• First offense: Fine of $500–$5,000, up to 2½ years in jail, and a one-year license suspension. First-time offenders may be eligible for the 24D disposition—probation with an alcohol/drug education program in exchange for reduced penalties.
• Second offense: Fine of $600–$10,000, 60 days to 2½ years in jail (30-day mandatory minimum), and a two-year license suspension.
• Third offense: Charged as a felony. Fine of $1,000–$15,000, 180 days to 5 years of incarceration (150-day mandatory minimum), and an eight-year license suspension.

A conviction also carries collateral consequences, including a $250 head injury assessment, significantly increased insurance costs, and a permanent mark on the driver’s record that affects the penalties for any future offense.

Can the RMV Revoke Your License Before a Conviction?

Yes. Under the Immediate Threat law (G.L. c. 90, § 22(a)), the Registry of Motor Vehicles can summarily revoke the license of a driver who has recently acted in a way that threatens public safety, which can include operating while impaired by marijuana.

The Immediate Threat statute allows the RMV to revoke a driver’s license or right to operate before any criminal conviction if the driver’s conduct is deemed a threat to public safety. Marijuana-impaired driving can trigger this kind of revocation.

A driver who believes an Immediate Threat revocation may result from a marijuana OUI arrest may wish to obtain a blood test as soon as possible to document THC levels. While THC concentration does not establish impairment, contemporaneous evidence can be relevant to a later challenge.

What Are Your Rights If Your License Is Revoked?

You have the right to a hearing before an RMV Hearings Officer, the right to be represented by an attorney, and the right to appeal to the Board of Appeal of the Division of Insurance, which can affirm, modify, or annul the RMV’s decision.

If the RMV revokes your license, you are entitled to due process:

• RMV hearing: You may request a hearing before a Registry Hearings Officer to contest the revocation.
• Right to counsel: You have the right to be represented by an attorney at these proceedings.
• Board of Appeal: You may appear before the Board of Appeal of the Division of Insurance, a quasi-judicial body with authority to affirm, modify, or annul any decision of the Registry.

These proceedings are separate from the criminal case, and each has its own procedures and deadlines. Prompt action is important to preserve your rights.

Facing a Marijuana OUI Charge or License Revocation in Massachusetts?

Marijuana OUI cases are legally and scientifically complex, and the evolving case law creates real opportunities to challenge the Commonwealth’s evidence. The Law Office of Brian Simoneau, P.C. represents drivers facing OUI-marijuana charges and license revocations, and handles RMV hearings and appeals before the Board of Appeal.

If you are facing a marijuana OUI charge or the loss of your license, call 508-625-5776 to discuss your options.