In Washington, regardless of age, it's illegal to drive or be in actual physical control of a motor vehicle while under the influence of drugs and/or alcohol. You can be convicted of "per se" DUI if you have a blood alcohol concentration (BAC) of .08% or more within two hours of driving or a "per se marijuana" DUI for driving with a concentration of five nanograms or more of THC (the primary psychoactive ingredient in marijuana) per milliliter of blood. And no matter what concentration of drugs or alcohol you have in your system, for driving while affected by alcohol and/or drugs, you can be convicted of an "impairment" DUI.
However, if you're younger than 21 years old, the legal limits are much lower: It's a misdemeanor—an offense called "underage DUI"—for drivers younger than 21 to have a BAC of .02% or more within two hours of driving or drive with any concentration of THC in the blood.
An underage DUI is a different crime than DUI, so it has different penalties. The most jail time you can get for an underage DUI is 90 days. (Drivers who are younger than 18 when convicted will serve any confinement in a juvenile detention facility.) The maximum fine is $1000 and you can receive up to two years of probation (see below).
An underage DUI conviction isn't considered a "DUI prior" under Washington law. So if you subsequently get another DUI, it will count as a first rather than a second offense. However, underage DUI convictions are part of the offender's criminal history. So the conviction could still have an impact on how the offender is sentenced for any crimes committed in the future.
Being underage doesn't shield a motorist who drives while impaired or with an alcohol or THC blood concentration that exceeds the limits for drivers who are 21 years or older from being convicted of a standard DUI. Underage drivers who are convicted of a standard DUI face the same consequences as drivers 21 or older. The possible penalties are:
Drivers convicted of a DUI can be placed on probation for up to five years. And if you miss a court date while on probation and the court issues a warrant, your probation period is tolled until you return—meaning, you could end up being on probation longer.
As conditions of DUI probation, the driver is prohibited from:
Drivers who violate any of these conditions face a mandatory 30 days jail in and 30 days of license suspension. (If the driver is already on a suspended license, the suspension is extended for 30 days.)
Penalties are harsher for motorists who refused chemical testing in violation of Washington's implied consent laws or had a BAC of .15% or more.
The Washington State Department of Licensing imposes two types of consequences for DUI-related crimes, regardless of a driver's age. An underage DUI or standard DUI arrest—where the driver's BAC or THC concentration exceeds the legal limit (see above)—triggers an administrative license suspension, even if the driver isn't later convicted of a crime in court.
The administrative suspension lasts for 90 days to two years. And if the driver is ultimately convicted of underage DUI or standard DUI (or a reduced crime that started as a DUI), there's another suspension that lasts for 90 days to four years. However, any time the driver has already completed the administrative suspension is credited against the criminal-conviction suspension. So a driver who gets a 90-day administrative suspension and another 90-day suspension for a DUI conviction will have to complete only 90 days total—not 180 days.
While your driver's license is suspended, you can get an IID license. An IID license allows you to drive a car equipped with an IID for the period of your suspension. IIDs are also required—for all drivers—for a period of time after the suspension is complete. The length of the IID time depends on the circumstances of the offense.