Massachusetts Marijuana Laws: Possession, Use, and Federal Limits

Under Massachusetts marijuana laws, adults 21 and older can carry up to two ounces in public, keep up to 10 ounces at home, grow up to six plants, and buy from licensed retailers. Voters approved Question 4 in 2016, and the rules now live in M.G.L. c. 94G. What trips people up is not the headline legality but the details around where you can use it, how you have to carry it in a car, and the places federal law still controls.

How Much You Can Have

In public, you can carry up to two ounces of marijuana, with no more than five grams in concentrate form.¹ The first ounce is fully protected: no fine, no arrest, no forfeiture.² Carrying between one and two ounces outside your home is a civil matter with a maximum $100 fine and forfeiture of the excess.³

At home the cap is 10 ounces. Anything over one ounce has to be kept in a locked container or locked room.² A safe, a locking cabinet, or a lockbox meets the requirement.

You can also give up to one ounce (no more than five grams concentrate) to another adult 21 or older, as long as no money or anything of value changes hands and the transfer isn’t advertised publicly.² Selling without a license is illegal at any quantity.

Growing at Home

One adult can grow up to six plants. If two or more adults 21 or older share a residence, the household cap is 12 plants total, no matter how many more adults live there.⁴ The limits apply only at your primary residence.

Every plant has to be in a locked area, whether that’s a room with a locking door, a padlocked grow tent, or a fenced outdoor garden with a locking gate.² Plants also cannot be visible from any public place without binoculars, aircraft, or similar equipment.⁴ Outdoor grows generally need solid fencing or screening, and indoor plants near ground-floor windows need to be placed out of sight.

Growing between 7 and 12 plants as a solo resident is a civil penalty of up to $100 plus forfeiture of the excess plants.³ Going well past the cap can trigger charges for unlicensed manufacturing or distribution.

Buying from a Dispensary

Every retail marijuana business in Massachusetts must hold a license from the Cannabis Control Commission.⁵ Bring valid government-issued photo ID showing you’re at least 21, whether you walk in or receive a licensed delivery at home.

The per-transaction limit is two ounces of flower. Until the Commission finalizes updated equivalency regulations, interim limits apply to other forms, including 10 grams of THC in concentrates and 1,000 milligrams of THC in edibles. Retailers track your purchase at the register.

Expect the price to climb at checkout. Adult-use marijuana carries three layers of tax:⁶

State sales tax of 6.25%
State excise tax of 10.75%
A local option tax of up to 3%, set by the city or town where the retailer sits

Combined, that can add up to roughly 20% over the shelf price. Most dispensaries still take only cash or debit because of federal banking restrictions. On-site ATMs are common but usually charge their own fee.

Where You Can and Can’t Use It

Public consumption is illegal in any form. Smoking, vaping, and edibles all fall under the ban, and a violation carries a civil fine of up to $100.³ The ban covers sidewalks, parks, school grounds, and anywhere tobacco smoking is already prohibited.

The one carve-out is a licensed social consumption establishment, essentially a cannabis lounge or café, in a city or town that has voted to allow them.³ A handful of municipalities have opted in; the licensed-location count is still small.

Rentals and Workplaces

A landlord can prohibit smoking marijuana inside a rental unit through a lease provision. A lease generally cannot ban possession or non-smoking methods like edibles or tinctures unless allowing them would put the landlord in violation of federal law or the property is government-owned.⁷ The federally assisted housing exception is a large one, and it’s covered below.

Employers keep full authority to run drug-free workplaces. A company can discipline or fire you for marijuana use even though it’s legal under state law, especially if you’re impaired at work. Federal contractors face additional obligations.

Marijuana and Driving

Driving under the influence of marijuana is prosecuted under the same statute as drunk driving, M.G.L. c. 90, § 24. A first offense carries a fine between $500 and $5,000, up to two and a half years in jail, or both.⁸ A conviction also costs you your license unless you qualify for an alternative disposition under Section 24D. Unlike alcohol, there’s no per se THC blood level that automatically equals impairment, so prosecutors rely on officer observations, field sobriety tests, and expert testimony.

Open Container Rule

Marijuana in a vehicle is treated like an open container of alcohol. If the dispensary seal is broken or the contents have been partially used, the product has to be in the trunk, a locked glove compartment, or behind the last upright seat in a vehicle without a trunk. It cannot sit anywhere in the passenger area accessible to the driver or passengers.³ A sealed, unopened dispensary container can stay in the passenger cabin.

Violating the rule costs up to $500, even if you’re completely sober and the marijuana was legally bought.³ This is one of the easiest fines to avoid and one of the most common to trigger by accident. If you’ve used any of the product, put the container in the trunk before you start the car.

People Under 21

Adults under 21 face civil penalties, not criminal charges, for most marijuana conduct. Buying, trying to buy, using a fake ID, or arranging for someone else to buy it draws a civil fine of up to $100 plus mandatory completion of a drug awareness program.³ For anyone under 18, parents or guardians are notified, and failing to finish the program within a year can lead to juvenile delinquency proceedings.

Underage cultivation of up to 12 plants carries the same structure: up to $100, a required awareness program, parental notification, and possible delinquency proceedings for those under 18 who don’t complete it.³ The program requirement is not optional, and ignoring it escalates the consequences.

Where Federal Law Still Wins

State legalization doesn’t override federal law. Several collisions trip up Massachusetts residents who assume state legality is all that matters.

Federal Property

National parks, military bases, federal courthouses, and any other federal land follow federal law, which still classifies marijuana as a controlled substance. Possession and use are prohibited at any National Park Service unit regardless of state law.⁹ In Massachusetts, that reaches the Cape Cod National Seashore, the Boston Harbor Islands, and other federal properties.

Firearms

Federal law makes it illegal for any “unlawful user of or addicted to any controlled substance” to possess a firearm or ammunition.¹⁰ Because marijuana is still federally illegal, a regular user is a prohibited person. ATF Form 4473, which you fill out when buying from a licensed dealer, asks whether you’re an unlawful user of a controlled substance. Answering truthfully blocks the sale. Answering falsely is a federal felony. There’s no clean resolution for Massachusetts residents who use marijuana and want to own firearms.

Crossing State Lines

Taking marijuana across any state border is a federal crime, even if both states have legalized it. Federal trafficking penalties start at up to five years in prison and a $250,000 fine for quantities under 50 kilograms. For a personal-use amount, federal prosecution is unlikely but possible, and the destination or transit state’s own laws may apply. The safe practice is not to carry it across any state line.

Federally Assisted Housing

If you live in public housing or use a federal housing voucher, marijuana use or possession can be grounds for eviction or denial of your application. The Quality Housing and Work Responsibility Act requires housing authorities to deny admission to anyone found using an illegal controlled substance at the time of application. For existing tenants, federal rules permit eviction for marijuana use, though it isn’t always mandatory. Federal housing programs follow federal drug classifications, not Massachusetts law.

1
Cannabis Control Commission Massachusetts. Know the Laws
2
General Court of Massachusetts. Massachusetts General Laws Chapter 94G Section 7 – Personal Use of Marijuana
3
General Court of Massachusetts. Massachusetts General Laws Chapter 94G Section 13 – Penalties
4
Cannabis Control Commission Massachusetts. Home Cultivation
5
Cannabis Control Commission Massachusetts. Where to Buy
6
Cannabis Control Commission Massachusetts. Sales and Product Distribution
7
Cannabis Control Commission. Guidance on Consumption of Marijuana for Adult Use
8
General Court of Massachusetts. Massachusetts General Laws Chapter 90 Section 24 – Driving Under the Influence
9
National Park Service. Marijuana and Other Substances – Bering Land Bridge National Preserve
10
Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts