Massachusetts legalized recreational marijuana when voters approved Question 4 in November 2016, and legal retail sales began on November 20, 2018. Medical marijuana came earlier, through Question 3 in November 2012.1Secretary of the Commonwealth of Massachusetts. 2016 Statewide Question 42General Court of Massachusetts. Acts of 2012 Chapter 369 – An Act for the Humanitarian Medical Use of Marijuana Adults 21 and older can now carry up to an ounce in public and keep up to ten ounces at home, but the rules around where you use it, how you drive after using it, and how federal law still treats it catch a lot of people off guard.
The Three Dates That Matter
Massachusetts moved toward legalization in stages. Voters passed the Medical Marijuana Initiative in November 2012, which let patients with qualifying conditions buy from licensed treatment centers. Four years later, in November 2016, voters passed the Marijuana Legalization Initiative, making recreational use legal for adults 21 and over and creating the Cannabis Control Commission to regulate the industry.
Retail stores did not open right away. The Commission spent nearly two years writing licensing and safety rules, and the first two dispensaries finally opened their doors on November 20, 2018. That made Massachusetts the first state on the East Coast to sell recreational marijuana.
How Much You Can Have
If you are 21 or older, you can carry up to one ounce of marijuana on your person, and no more than five grams of that total can be in concentrate form. At home, the limit rises to ten ounces, plus whatever your plants produce.3General Court of Massachusetts. Massachusetts General Laws Ch. 94G Section 7 – Personal Use of Marijuana You can give away up to one ounce to another adult, as long as you do not advertise it and do not charge anything.
Home growing is capped at six plants per adult and twelve per household, regardless of how many adults live there. Plants have to be in a space with a lock or similar security device and cannot be visible from a public area without binoculars. If your plants can be seen from the street, you face a civil penalty of up to $300 and forfeiture of the plants. Growing between seven and twelve plants (over the per-person cap but under the household cap) carries a $100 fine plus loss of the extra plants.4Cannabis Control Commission Massachusetts. Home Cultivation
Where You Can Actually Use It
Legal to possess does not mean legal to use anywhere. You cannot consume marijuana in any public place, and you cannot smoke it anywhere tobacco smoking is prohibited. A violation is a civil offense with a fine of up to $100.5General Court of Massachusetts. Massachusetts General Laws Ch. 94G Section 13 – Penalties The only exception is a licensed marijuana establishment in a city or town that has voted to allow on-site consumption.
Vehicles have their own rule. You cannot have an open container of marijuana anywhere in the passenger area of a vehicle on a road or in a place the public can access. An “open container” is any package with a broken seal or partially consumed contents. The passenger area is everything a driver or passenger can reach while seated, which does not include the trunk or a locked glove compartment. An open-container violation is a civil fine of up to $500. The safe practice is to keep sealed products in the trunk.
What Happens if You Go Over the Limit
The gap between legal and criminal is sharper than many people realize. In public, anything over one ounce is a criminal offense. At home, anything over ten ounces is the same. There is no civil-fine cushion for adults who are slightly over.
Under the controlled substances statute, possessing more than one ounce of marijuana is punishable by up to six months in jail, a fine of up to $500, or both.6General Court of Massachusetts. Massachusetts General Laws Ch. 94C Section 34 A second or subsequent conviction for any controlled substance possession increases the maximum to two years in jail and a $2,000 fine.
People under 21 are handled differently. A minor caught with marijuana faces a civil penalty of up to $100 and must complete a drug awareness program, and parents or guardians have to be notified.7General Court of Massachusetts. Massachusetts General Laws Ch. 94C Section 32L Not finishing the program within a year pushes the penalty to $1,000, with the minor and their parents jointly responsible for the amount.
Driving After Using Marijuana
Legalization did not change the state’s drugged-driving law. Massachusetts treats marijuana-impaired driving under the same OUI statute as alcohol, and the penalties mirror those for drunk driving. A first offense carries a fine of $500 to $5,000, up to two and a half years in jail, or both, and most first offenders are routed into a driver alcohol education program with a one-year license revocation. A second offense brings 60 days to two and a half years in jail, with a mandatory minimum of 30 days that cannot be suspended, and a two-year license revocation.8General Court of Massachusetts. Massachusetts General Laws Ch. 90 Section 24
Massachusetts has no specific blood-THC threshold for a per se violation. Prosecutors rely on officer observations, field sobriety tests, and other evidence of impairment. That cuts both ways: there is no number that automatically convicts you, but there is also no number that automatically clears you.
Federal Rules That Still Apply
Marijuana remains a Schedule I controlled substance under federal law, and that classification creates real consequences in a few specific situations even for Massachusetts residents who never leave the state.
Firearms
Federal law prohibits any “unlawful user of or addicted to any controlled substance” from possessing firearms or ammunition.9Office of the Law Revision Counsel. United States Code Title 18 Section 922 – Unlawful Acts Because marijuana is federally illegal regardless of state law, a Massachusetts resident who uses marijuana and owns a gun is technically committing a federal felony punishable by up to 15 years in prison. Every gun buyer at a licensed dealer fills out ATF Form 4473, which asks directly whether the buyer is an unlawful user of marijuana or any other controlled substance. Answering “no” while using marijuana is a separate federal crime. As of early 2026, the Supreme Court is considering a challenge to this restriction, but the prohibition stands until the Court rules.
Air Travel
Airport checkpoints and airplanes operate under federal jurisdiction. TSA officers do not actively hunt for marijuana, but if screeners find it, they are required to refer the matter to local law enforcement. What happens from there depends on the responding agency and the airport’s local policy. Carrying marijuana onto a flight also violates federal aviation regulations, which prohibit operating a civil aircraft with knowledge that a controlled substance is aboard.
Federal Housing
Residents of public housing and Section 8 units face a distinct risk. The U.S. Department of Housing and Urban Development can remove tenants who use any controlled substance on the premises, and that includes state-legal marijuana, including medical marijuana. Losing a federally subsidized unit over conduct that is perfectly legal under Massachusetts law is a real possibility.
Clearing a Past Marijuana Conviction
If you have a Massachusetts conviction for conduct that would be legal today, you can petition to have it erased. A 2022 provision requires the court to order expungement within 30 days of receiving your petition if the conviction involved possession, cultivation, or distribution of an amount of marijuana that has since been decriminalized or legalized.10Mass.gov. Massachusetts General Laws Ch. 276 Section 100K 1/4 – Expungement of Marijuana Records That covers offenses reached by the 2008 decriminalization law (one ounce or less), the 2016 legalization initiative, and the 2017 implementing legislation, including possession-with-intent and distribution charges as long as the amount is now legal.
Either you or the district attorney can request a hearing, but the 30-day clock is mandatory. Once the court grants the petition, it notifies the commissioner of probation and the commissioner of criminal justice information services, and the records are destroyed. The general expungement framework for other types of convictions has more restrictions and longer timelines.11Mass.gov. Massachusetts General Laws Ch. 276 Sections 100E-100U – Expungement