In Washington, an adult 21 or older can have up to the legal possession limit in a car (1 ounce of flower, 7 grams of concentrate, 16 ounces of solid edibles and 72 ounces of infused liquids), but anything opened must be in the trunk. An opened package in the passenger area, including the glove box, is a traffic infraction, and so is using cannabis in a vehicle on a public road.
That covers the amount. The harder questions are about how it is packed, who in the car is responsible, and what happens if the driver has used cannabis at all. Washington answers them in one vehicle statute, RCW 46.61.745, and its DUI law, RCW 46.61.502. This page goes through both, as of October 29, 2026. For everything else, from purchase rules to taxes, see the Washington marijuana laws guide.
Washington cannabis-in-the-car rules at a glance
| Situation | Rule | Source |
|---|---|---|
| Sealed, unopened store package anywhere in the car | Allowed, within the possession limit | RCW 46.61.745(1)(a)(i)(C) |
| Opened package in the trunk | Allowed | RCW 46.61.745(1)(a)(i)(A) |
| Opened package in the cabin, console or glove box | Traffic infraction | RCW 46.61.745(1)(a)(i) |
| Anyone smoking, vaping or eating cannabis in the car on a public road | Traffic infraction | RCW 46.61.745(1)(a)(ii) |
| Cannabis hidden in a container labeled as something else | Traffic infraction if kept in the cabin | RCW 46.61.745(1)(a)(iii) |
| Driver 21+ with 5.00 ng/mL or more of THC within two hours | Per se DUI, a gross misdemeanor | RCW 46.61.502 |
| Driver under 21 with any THC above 0.00 | Misdemeanor | RCW 46.61.503 |
How much weed can you legally have in your car?
The same amount you can legally possess anywhere in Washington: 1 ounce of usable cannabis, 7 grams of concentrate, 16 ounces of solid infused products and 72 ounces of infused liquids for each adult 21 or older. Those amounts come from RCW 69.50.4013(3), which points back to the limits in RCW 69.50.360(3). There is no special, larger “vehicle” allowance and no smaller one.
Each adult in the car carries their own limit, which matters when three friends leave a store together. What the law looks at is who possesses what, so keep each person’s purchase in its own bag with its own receipt rather than pooling everything into one sack. Registered medical patients in the Department of Health database can possess more under the medical statute; ordinary adults cannot.
The amount is rarely the problem on a traffic stop. Packaging and location are.
Is an open package in the car illegal in Washington?
Yes. Keeping cannabis in the passenger area of a vehicle on a highway is a traffic infraction unless the package has never been opened, the seal is intact and nothing has been removed. The vehicle statute applies to “the registered owner of a motor vehicle, or the driver if the registered owner is not then present, or passengers in the vehicle.”
RCW 46.61.745 gives three safe places for cannabis while the car is on a public road:
- The trunk. Opened or not, cannabis in the trunk is outside the rule.
- Somewhere the driver and passengers cannot reach, if the vehicle has no trunk. Think of a locked cargo box or the back of an SUV that is not normally occupied or directly accessible. A hatchback cargo area that a passenger can reach over the seat is a judgment call; the trunk rule is safer.
- A sealed package, “a package, container, or receptacle that has not been opened or the seal broken or contents partially removed.”
The statute then closes the most common loophole in one sentence: “A utility compartment or glove compartment is deemed to be within the area occupied by the driver and passengers.” The LCB’s consumer page, Using and Having Cannabis, puts it plainly: “The glove compartment is not an acceptable storage area,” and cannabis in a vehicle must be in its original container with an unbroken seal unless it is in the trunk.
Two practical traps. A half-smoked joint or a vape cartridge you have already used is an opened product, even if it went back into the original box. And moving cannabis into an unmarked tin or a container labeled as something else does not help: the statute makes that its own violation when the container is kept in the cabin, and a mislabeled original container creates a presumption against you.
The rule is written for vehicles “upon a highway,” which Washington defines in RCW 46.04.197 as the full width of any publicly maintained way open to vehicle traffic. That covers city streets as well as freeways. A car parked in a private driveway is outside this particular statute, though other laws still apply.
Can a passenger smoke in the car in Washington?
No. Consuming cannabis “in any manner including, but not limited to, smoking or ingesting” in a motor vehicle on a public highway is a traffic infraction, and the rule is not limited to the driver. Passengers are covered, rideshares and limousines are motor vehicles like any other, and there is no exception for a parked car on a public street.
Eating an edible counts, because the statute says “in any manner.” So does vaping. A passenger who smokes in the back seat also creates problems for the driver beyond the ticket. The smell of fresh smoke can draw an officer’s attention to whether the driver is impaired, and a smoke-filled car is a poor start to any traffic stop. Visible use from a car parked on the street can also fall under the separate public-use ban in RCW 69.50.445, which covers using cannabis “in view of the general public.”
The legal place to use cannabis in Washington is private property with the owner’s permission. A car on a public road is not one of them.
What is the DUI limit for THC in Washington?
Washington’s per se limit is 5.00 nanograms of THC per milliliter of blood, measured within two hours after driving; drivers under 21 may have no THC above 0.00. A driver at or over 5.00 is guilty of DUI under RCW 46.61.502 on the number alone. The under-21 rule is RCW 46.61.503.
The number is not the whole law. RCW 46.61.502 also makes it DUI to drive “while the person is under the influence of or affected by” cannabis, so a driver can be charged below 5.00 based on driving behavior and officer observations. Blood drawn more than two hours after driving can still be used as evidence, and any THC above 0.00 can support an “affected by” charge. A first DUI is a gross misdemeanor. It becomes a class B felony with three or more prior offenses within 15 years, or with certain earlier vehicular homicide or assault convictions.
Two points surprise people:
- A medical authorization is no defense. The statute says being “entitled to use a drug under the laws of this state shall not constitute a defense.” Patients face the same DUI law as everyone else.
- There is no reliable “wait time.” THC levels after smoking, vaping or eating vary from person to person and product to product, and Washington law does not offer a safe number of hours. If you have used cannabis, do not drive.
Plan the ride before you shop. Our Seattle, Tacoma and Spokane directory pages list stores by neighborhood so you can pick one close to where you are staying.
Can you drive across a state line with weed?
No. Driving cannabis out of Washington into any other state or into Canada is illegal under federal law, even when the other side is legal. The trunk rule only protects you on Washington roads. Idaho has not legalized cannabis at all, and crossing the Canadian border with cannabis in either direction is illegal. See our federal marijuana law guide and the Oregon marijuana laws guide for the Columbia River crossing.
What this means for you
Before you pull out of the store parking lot, put opened products and anything you plan to open later in the trunk, leave sealed packages sealed, and keep the receipt. Nobody in the car should smoke, vape or eat cannabis on the road, and the person behind the wheel should not have used it. If you are visiting, choose a store near your lodging or on transit; the Washington dispensary directory lists every licensed store in the state. For how other states treat cannabis in cars, start at our cannabis laws hub.
Weed in the Car in Washington FAQ
Can I keep weed in my glove box in Washington?
Only if the package is sealed and unopened. Washington law treats the glove compartment and other utility compartments as part of the passenger area, so an opened package there is a traffic infraction.
Is it legal to drive home from the dispensary with weed?
Yes. A sealed store package within the possession limit is legal in the car. Keep it sealed, or put it in the trunk, until you are home.
Can you get a DUI for weed if you are not high?
Yes, if a blood test shows 5.00 ng/mL of THC or more within two hours of driving, which is a per se DUI regardless of how you feel. Drivers under 21 can be charged with any measurable THC.
Can I smoke weed in a parked car in Washington?
Not on a public street or road: the vehicle statute covers consumption in a vehicle “upon the public highway,” and use in view of the public is a separate civil infraction. A car on private property with the owner’s permission is a different question, but never drive afterward.
Can a passenger hold the weed in their lap if it is sealed?
Yes. A package that has never been opened, with its seal intact and nothing removed, may be in the passenger area. Once it is opened, it belongs in the trunk.
Do the car rules apply to edibles and vape cartridges?
Yes. The statute uses the full legal definition of cannabis, which covers flower, concentrates, cartridges and infused products. An opened edible package or a used cartridge belongs in the trunk.
Rules as of October 29, 2026. Laws change; check the linked statutes or the Washington State Liquor and Cannabis Board for current rules. Never drive impaired. General information, not legal advice.