As of September 26th it is illegal to have an open container of Marijuana in your vehicle. Just as an open container of alcohol is. Marijuana must be in its original sealed package and stored in the trunk of your car or behind the backseat. This law also extends to pot-infused edibles, like cookies and candies. Driving with an open container of marijuana is a traffic infraction, with a fine of $136.00.  The Washington Traffic Safety Commission pushed for the change so that the state’s rules governing marijuana would more closely resemble those for alcohol, which already prohibit unsealed or partially consumed containers of alcohol in the passenger cabin of a vehicle.