Washington State Marijuana Laws: Limits, DUI, and Penalties

Washington State’s marijuana laws let adults 21 and older buy cannabis from licensed retailers and possess limited amounts, but they draw hard lines around public use, driving, home growing, and federal property. The rules below cover what you can carry, where you can use it, what happens if you drive after consuming, and the narrower rights available to medical patients.

How Much You Can Legally Have

You must be 21 to buy or possess cannabis for recreational use. The state caps the amount you can carry or keep at home:

Up to one ounce (28 grams) of usable marijuana (flower)
Up to 16 ounces of solid edibles
Up to 72 ounces of liquid infused products
Up to seven grams of concentrates

Going over the flower limit puts you into criminal territory fast. Possession of more than one ounce but no more than 40 grams is a misdemeanor under RCW 69.50.4014, carrying up to 90 days in jail and up to a $1,000 fine, though the statute pushes prosecutors toward substance-use assessment and treatment instead of jail.¹ Above 40 grams, it becomes a felony punishable by up to five years in prison and a $10,000 fine, and prosecutors can add charges for intent to distribute at that quantity.

Anyone under 21 is barred from possessing cannabis in any amount under RCW 69.50.4013, with penalties up to 90 days in jail and a $1,000 fine plus referral to drug education. The only exception is a qualifying medical patient with a valid authorization.²

Where You Can Use Cannabis

Buying legally and using legally are two different questions. Use it in the wrong place and the penalties stack up in ways that surprise people.

Public Places Are Off-Limits

Using cannabis in any public place, or within view of the public, is a class 3 civil infraction under RCW 69.50.445 with a maximum fine of $50.³ Parks, sidewalks, streets, and anywhere the public can see you all count. Private residences are the safest option, with the caveats below for renters.

Federal Land Inside the State

Cannabis is still a Schedule I controlled substance under federal law, and federal rules govern any federally managed land inside Washington. Olympic National Park, Mount Rainier, North Cascades, and every other National Park Service site prohibit possession and use regardless of state legalization.⁴ The same goes for military bases and federal courthouses. Enforcement is federal, and state protections don’t apply.

Airports and Flying

At Sea-Tac, Washington’s possession limits apply inside the terminal, so carrying a legal amount through the airport won’t trigger state enforcement. TSA screeners don’t hunt for marijuana, but if they find it during a routine search, federal policy requires them to notify local law enforcement, which at Sea-Tac usually means being asked to dispose of it if you’re within state limits. Once you board a plane, you’re under federal jurisdiction, and possessing cannabis on the aircraft is a federal crime no matter where you’re flying.

Driving After Using Cannabis

Washington treats cannabis-impaired driving the same as drunk driving. A DUI conviction follows you for years and hits your license, insurance, and job prospects.

The THC Limit

For drivers 21 and older, the per se limit is 5.00 nanograms of active THC (delta-9) per milliliter of blood, measured within two hours of driving.⁵ The number alone is enough for a charge; the prosecution doesn’t have to prove you were driving badly.

For drivers under 21, the standard is zero tolerance. Any detectable amount above 0.00 nanograms per milliliter is grounds for a charge under RCW 46.61.503.⁶ THC can linger in blood for hours, so young drivers who consume need real time before getting behind the wheel.

Blood Tests and Implied Consent

There’s no roadside breath test for cannabis. Officers who suspect impairment request a blood draw. Under Washington’s implied consent law, driving on state roads means you’ve already agreed to submit if an officer has reasonable grounds to believe you’re impaired. Refusing the test triggers an automatic license revocation of at least a year, and the refusal itself can be used against you at trial.⁷

DUI Penalties

A first cannabis DUI, with no prior offenses in the previous seven years, carries a mandatory minimum of 24 consecutive hours in jail (or 15 days of electronic home monitoring as an alternative) and a fine between $350 and $5,000. The $350 minimum fine can’t be suspended unless you can show you’re unable to pay.⁸ Second and subsequent offenses within seven years bring longer mandatory jail time, higher fines, and extended license suspensions.

How to Transport Cannabis

Even sober, how you carry cannabis in your car matters. RCW 46.61.745 requires it to be in the trunk, in an area not accessible to the driver or passengers, or in a sealed container that hasn’t been opened. Glove compartments and center consoles count as accessible, so those don’t work. Violating the rule is a traffic infraction.⁹

What You’ll Pay at the Register

Washington’s cannabis taxes are among the highest in the country. The state charges a 37% excise tax on every retail sale, on top of standard state and local sales taxes.¹⁰ The excise tax has to appear separately on your receipt from regular sales tax.

Payment is the other thing that catches people out. Because cannabis remains federally illegal, most major banks and card networks won’t process cannabis transactions, so most dispensaries are cash-only. Many have on-site ATMs. Bring cash and you’ll avoid the surprise at the counter.

Home Growing Is Still a Felony

Growing your own cannabis for recreational use is a felony in Washington. This surprises people who assume that legalization brought home cultivation along with it. Without a medical authorization, plants at your residence can support a charge of manufacturing a controlled substance.¹¹

Legislative attempts to change this have stalled. Senate Bill 6204, introduced in the 2025–2026 session, would have allowed adults 21 and older to grow up to six plants each with a 15-plant household cap. As of 2026, the bill was moved to the Senate Rules “X” file, effectively shelving it without a vote.¹² Until something passes, recreational home cultivation carries the same penalty as illegal manufacturing.

Medical Patients Can Grow

The exception is for qualifying medical patients. What you can grow depends on whether you’ve registered in the state’s medical cannabis authorization database:

Registered patients with a recognition card can grow up to six plants at home for personal medical use, with up to 15 possible if a healthcare professional determines their needs exceed the standard amount. Registered patients may also possess up to eight ounces of usable cannabis from their own plants.¹³
Authorization-only patients without a recognition card can grow up to four plants and possess up to six ounces at home.¹³

All medical cultivation must happen in the patient’s residence and can’t be visible from public view. Keep your authorization paperwork or recognition card where you can produce it. Without it, law enforcement has no way to tell a legal medical grow from an illegal recreational one.

The Medical Marijuana Program

Washington’s medical program predates recreational legalization and gives patients higher limits and a tax break that recreational buyers don’t get.

Qualifying Conditions

A healthcare professional can authorize medical cannabis for the following:¹⁴

Cancer
HIV
Multiple sclerosis
Epilepsy or other seizure disorders, or spasticity disorders
Intractable pain not relieved by standard treatments
Glaucoma with increased intraocular pressure unresponsive to standard treatments
Crohn’s disease with debilitating symptoms unresponsive to standard treatments
Hepatitis C with debilitating nausea or intractable pain
Diseases resulting in nausea, vomiting, wasting, appetite loss, cramping, seizures, muscle spasms, or spasticity (including anorexia)
Chronic renal failure requiring hemodialysis
PTSD
Traumatic brain injury

Why the Recognition Card Is Worth It

Getting an authorization from a provider is step one. Registering in the state database and getting a recognition card is what unlocks the higher limits and tax savings. Cardholders can possess up to three ounces of usable cannabis, 48 ounces of solid edibles, 216 ounces of liquid products, and 21 grams of concentrates. They are also exempt from the 37% cannabis excise tax when buying from a retailer with a medical endorsement.¹⁰ If you buy often, that exemption alone can justify the registration effort.

For patients under 21, the recognition card is the only way to legally possess cannabis in Washington. A parent or legal guardian must consent and serve as the designated provider.

Jobs and Drug Testing

Washington changed the ground rules for employers on January 1, 2024. Under RCW 49.44.240, it is illegal for an employer to reject a job applicant based on off-duty cannabis use or on a pre-employment drug test that detects nonpsychoactive cannabis metabolites.¹⁵ The distinction matters: nonpsychoactive metabolites can stay in your system for weeks and only show past use. Employers can still use testing methods that detect active THC, a better indicator of recent use.

These protections apply only to hiring. Employers can still test after a workplace accident or when they suspect an employee is impaired on the job. They also keep the right to maintain drug-free workplace policies where federal law requires it.

Jobs the Law Doesn’t Cover

Several categories are carved out. If you’re applying for any of the following, an employer can still reject you based on a positive cannabis test:¹⁵

Law enforcement officers with a general authority Washington agency
Firefighters and fire protection district personnel
First responders and dispatchers, including 911 operators and emergency medical service providers
Corrections officers and anyone directly responsible for custody and security at jails or detention facilities
Positions requiring a federal background investigation or security clearance
Airline and aerospace industry positions
Other safety-sensitive roles where impairment creates a substantial risk of death, as identified by the employer before you apply

If You Rent

Owning your home gives you the widest room to use cannabis at home. Renting is narrower. Landlords and property managers in Washington can prohibit smoking, vaping, and cultivation through lease terms, and a no-smoking clause covers cannabis just as it covers tobacco. Breaking those terms can trigger a 10-day comply-or-vacate notice and eventually eviction.

Federally subsidized housing is stricter. Public housing authorities and Section 8 landlords have to follow federal rules, and under those rules, marijuana use is grounds for denial of admission or eviction regardless of Washington law. That applies even to medical patients with valid state authorizations. If you live in federally assisted housing, state legalization does not protect you.

1
Washington State Legislature. RCW 69.50.4014 – Possession of Forty Grams or Less of Cannabis
2
Washington State Legislature. RCW 69.50.4013 – Possession of Controlled Substance
3
Washington State Legislature. RCW 69.50.445 – Opening Package of or Consuming Cannabis in View of General Public or Public Place
4
National Park Service. Know the Rules
5
Washington State Legislature. RCW 46.61.502 – Driving Under the Influence
6
Washington State Legislature. RCW 46.61.503 – Driving After Consuming Alcohol or Cannabis Under Age 21
7
Washington State Legislature. RCW 46.20.308 – Implied Consent
8
Washington State Legislature. RCW 46.61.5055 – Alcohol and Drug Violators Penalty Schedule
9
Washington State Legislature. RCW 46.61.745 – Keeping Cannabis in a Motor Vehicle
10
Washington State Legislature. RCW 69.50.535 – Cannabis Excise Tax
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Washington State Legislature. RCW 69.50.401 – Prohibited Acts A – Penalties
12
Washington State Legislature. SB 6204 – 2025-26
13
Washington State Legislature. RCW 69.51A.210 – Recognition Card Holders and Designated Providers
14
Washington State Legislature. Washington Code Chapter 69.51A RCW – Medical Cannabis
15
Washington State Legislature. RCW 49.44.240 – Discrimination Based on Cannabis Use