In Washington Driving Under the Influence (DUI) refers to operating a motor vehicle while affected by alcohol, drugs, or both. This law applies to both legal and illegal drugs, including prescription medication and over-the-counter drugs.

If DUI is suspected, the amount of alcohol in the driver's blood is measured by a breath or blood test. The driver will be cited for DUI if the results are .08 or higher for adults or .02 or higher for minors (under 21).

Refusal to take a chemical test can be used against you in court, and also result in harsher penalties in court and with your driving privilege. When you operate a motor vehicle in Washington State, you automatically give consent to have your breath or blood tested if a law enforcement officer believes you have been driving under the influence of alcohol or drugs. This is known as Washington's Implied Consent law.

A DUI conviction may be included as a prior conviction for 7 years.

Washington has many unique policies and procedures related to DUI arrests which make it extremely important to retain a qualified Washington DUI defense lawyer who is familiar with the prosecutors and local practices.