In Washington State, the legal blood alcohol concentration (BAC) limit is 0.08% for drivers 21 and older operating a standard passenger vehicle. Commercial drivers face a stricter limit of 0.04%, and drivers under 21 are subject to Washington's zero-tolerance law, which sets the limit at just 0.02%. Registering at or above the applicable limit gives law enforcement grounds to charge you with DUI under RCW 46.61.502, and the consequences — including license suspension and potential jail time — can begin almost immediately.
What BAC Limits Apply in Washington, and Who Do They Cover?
Washington law sets different BAC thresholds depending on who is behind the wheel. Understanding which limit applies to you is the first step in understanding your legal exposure.
- Standard drivers (21 and older): 0.08% BAC. At or above this level, you are presumed impaired under RCW 46.61.502 regardless of how you feel or how you drive.
- Commercial drivers: 0.04% BAC. If you hold a commercial driver’s license (CDL) and are operating a commercial vehicle, the threshold is cut in half. A CDL violation can end a career, not just result in fines.
- Drivers under 21: 0.02% BAC. Washington’s zero-tolerance law means even a single drink can push a young driver over the legal limit. This is not a rounding error — 0.02% is intentionally set low to deter underage drinking and driving entirely.
It is also worth knowing that Washington law covers more than alcohol. RCW 46.61.502 makes it unlawful to drive while affected by any drug — including marijuana, prescription medications, or a combination of substances — if your ability to drive is appreciably impaired. There is no single THC number that automatically equals a DUI the way 0.08% does for alcohol, but that does not mean cannabis is a safe defense.
Does Being Under 0.08% Mean You Are Safe from a DUI Charge?
Not necessarily. This surprises many people. Washington law has two separate paths to a DUI conviction:
- Per se DUI: Your BAC is at or above the legal limit. The prosecution does not need to prove impairment beyond the number itself.
- Affected-by DUI: Your BAC is below 0.08%, but the officer and prosecution argue that alcohol or drugs appreciably affected your ability to drive safely. Field sobriety test results, driving behavior, and officer observations all factor in here.
In our experience handling DUI cases in Spokane County, we routinely see clients charged with DUI who blew below 0.08%. Prosecutors use dashcam footage, officer testimony, and field sobriety results to build those cases. A lower BAC does not automatically mean the case goes away — it means the defense strategy shifts.
How Is BAC Measured in Washington?
Law enforcement in Washington primarily uses two methods to establish BAC:
- Breath test (Breathalyzer): The most common method during a traffic stop. Washington uses the DataMaster DMT device at police stations after arrest. The roadside portable breath test (PBT) is used to establish probable cause but is generally not admissible as evidence of your actual BAC at trial.
- Blood draw: Used when a breath test is unavailable, when the driver is unconscious or hospitalized, or when drugs are suspected. Blood draws must follow strict procedural rules, and the sample must be properly preserved and analyzed.
Both methods have known sources of error — everything from equipment calibration issues to medical conditions like GERD that can affect breath results. An experienced DUI attorney will scrutinize the testing procedure carefully, because a flawed result can be challenged in court.
What Happens If You Refuse the Breath Test?
Washington’s implied consent law means that by driving on Washington roads, you have already agreed to submit to a breath or blood test if lawfully arrested for DUI. Refusing the test after a lawful arrest carries its own separate consequences — including a longer license revocation than you would face for a first-offense DUI with a test result. Refusal can also be used against you at trial as evidence of consciousness of guilt.
Refusal is not a loophole. In many cases it makes the situation harder, not easier. If you have questions about whether to take or refuse a test after an arrest, that decision needs to happen fast — ideally after a quick call to a criminal defense attorney.
What Are the Immediate Consequences of Exceeding the BAC Limit in Spokane?
A DUI arrest in Spokane County triggers two separate processes that run on different tracks and different timelines:
- Criminal case: Handled in Spokane District Court or Spokane County Superior Court depending on the circumstances. Penalties for a first-offense DUI in Washington can include mandatory minimum jail time, fines, ignition interlock device requirements, and probation.
- DOL administrative action: The Washington Department of Licensing (DOL) will move to suspend or revoke your license independent of the criminal case. You have a limited window — typically just a few days after arrest — to request a hearing to contest that suspension. Missing that deadline usually means automatic suspension.
The dual-track nature of DUI cases in Washington is one reason why acting quickly matters. For a deeper look at what happens to your driving privileges, see our related article on whether you will lose your license after a DUI in Washington. If cost is a concern, our overview of how much a DUI costs in Washington State breaks down what you are likely facing financially.
Should You Talk to a DUI Attorney Even If You Think the Case Is Simple?
Yes — and the sooner the better. DUI cases involve technical evidence, strict deadlines, and consequences that follow you long after the case closes. Even a first offense can affect your insurance rates, professional licenses, and employment background checks for years.
At Schwab Law, P.L.L.C., our attorneys handle DUI cases in Spokane and throughout Eastern Washington every week. We know the local courts, the prosecutors, and the procedural details that can make a meaningful difference in how a case resolves. If you or someone you care about is facing a DUI charge, we encourage you to contact our Spokane DUI defense team for a consultation before making any decisions about your case.
This article is general legal information about Washington DUI law and is not legal advice for your specific situation. Laws and procedures can change. Please consult a licensed Washington attorney about the facts of your case.
Key takeaways
- Washington's standard BAC limit is 0.08% for drivers 21 and older — at or above this level, impairment is presumed by law.
- Commercial drivers face a 0.04% limit; drivers under 21 are subject to a near-zero-tolerance limit of 0.02%.
- You can be charged with DUI even below 0.08% if alcohol or drugs appreciably impaired your driving ability.
- Refusing a breath test after a lawful arrest triggers its own license consequences and can be used against you in court.
- A DUI in Washington triggers two separate timelines — criminal court and a DOL license action — and you typically have only days to request a hearing on the license suspension.
Frequently asked questions
Is Washington's 0.08% BAC limit the same for marijuana?
No. Washington does not use a simple per se BAC-style limit for marijuana the way it does for alcohol. While a THC level of 5 nanograms per milliliter in blood creates an inference of impairment under Washington law, prosecutors can still charge you with a drug-affected DUI based on officer observations and other evidence even if your THC level is below that threshold.
How long does alcohol stay in your system at a detectable level in Washington?
This varies based on your weight, metabolism, how much you drank, and how quickly. As a rough general guide, the body processes roughly one standard drink per hour, but there is no reliable formula — breathalyzers and blood tests can detect alcohol for many hours after your last drink. Do not try to calculate your own BAC to decide whether it is safe to drive.
Can a BAC test result be challenged in a Washington DUI case?
Yes. Both breath and blood test results can be challenged on grounds including improper calibration of the testing device, failure to follow required observation periods before a breath test, chain of custody issues with blood samples, and medical conditions that affect readings. An experienced DUI defense attorney will evaluate the testing procedure as a core part of your defense.
How long do I have to request a DOL hearing after a DUI arrest in Washington?
Generally, you have a very short window — often around 20 days from the date of your arrest or the date you receive a notice of suspension — to request a DOL hearing to contest your license suspension. Missing this deadline typically results in automatic suspension. Contact an attorney immediately after a DUI arrest so this deadline is not missed.
Helpful resources
- RCW 46.61.502 — Driving Under the Influence (Washington Legislature)
- Washington State Department of Licensing — DUI
- Washington Courts — DUI Information
- Spokane County Superior Court
Have a dui / dwi question about your own situation? Learn more about how we can help, or call Schwab Law, P.L.L.C. at (509) 795-1894 for a consultation.
This article is general information about Washington law and is not legal advice. Reading it does not create an attorney-client relationship. Laws change and every situation is different — for advice about your specific circumstances, please consult a licensed Washington attorney.
