7.3 Impaired Driving, Implied Consent & Underage Zero Tolerance
Key Takeaways
- Washington's per se thresholds are an alcohol concentration of 0.08 or higher, or a THC concentration of 5.00 or higher, within two hours after driving, alongside a separate affected-by-impairment standard.
- RCW 46.61.503 makes it a misdemeanor for a driver under 21 to have an alcohol concentration of at least 0.02, or a THC concentration above 0.00, within two hours after driving or being in physical control.
- Under RCW 46.20.3101(1), a first test refusal within seven years is a one-year revocation and a second or subsequent refusal within seven years is a two-year revocation or until the person reaches 21, whichever is longer.
- A first test failure at 0.08 or more alcohol, or 5.00 or more THC, within seven years is a 90-day suspension unless the person completes or enrolls in a pretrial 24/7 sobriety program; a second or subsequent incident is a two-year revocation.
7.3 Impaired Driving, Implied Consent & Underage Zero Tolerance
[!NOTE] Two tracks, one traffic stop. A single impaired-driving arrest produces a criminal case under chapter 46.61 RCW and a separate administrative licence action by the Department of Licensing under RCW 46.20.308 and RCW 46.20.3101. They have different standards, different timelines and different outcomes. A driver can be acquitted in court and still lose the licence administratively.
The per se and affected-by standards
RCW 46.61.502 makes a person guilty of driving under the influence if, within two hours after driving, they have an alcohol concentration of 0.08 or higher as shown by analysis of breath or blood made under RCW 46.61.506, or a THC concentration of 5.00 or higher as shown by blood analysis under RCW 46.61.506, or if the person is under the influence of or affected by intoxicating liquor, cannabis, or any drug, or by a combination of them.
Two consequences for teaching:
- The affected-by prong means a person can be convicted below the per se numbers. There is no safe number.
- Both prongs are measured within two hours after driving, not at the moment of driving. RCW 46.61.503(4) confirms that analyses obtained more than two hours after may still be used as evidence of the concentration within two hours.
RCW 46.61.504 creates the parallel offence of physical control of a vehicle while under the influence, which reaches a person in control of a vehicle that is not moving. Both RCW 46.61.503(3) and the physical-control statute contain an affirmative defence where, prior to being pursued by a law enforcement officer, the person moved the vehicle safely off the roadway.
The under-21 rule
RCW 46.61.503(1) - a person is guilty of driving or being in physical control after consuming alcohol or cannabis if the person is under 21 and has, within two hours after operating or being in physical control, either:
- (i) an alcohol concentration of at least 0.02 but less than the concentration specified in RCW 46.61.502; or
- (ii) a THC concentration above 0.00 but less than the concentration specified in RCW 46.61.502.
RCW 46.61.503(5): "A violation of this section is a misdemeanor."
Note the precision of the cannabis standard for minors: above 0.00, which is a true zero-tolerance rule and not the adult 5.00 threshold. And note the structure: RCW 46.61.503 is a lesser offence occupying the band below the adult per se levels. A driver under 21 at 0.10 is charged under RCW 46.61.502, not RCW 46.61.503.
| Driver | Alcohol | THC |
|---|---|---|
| Any driver, per se DUI (RCW 46.61.502) | 0.08 or higher | 5.00 or higher |
| Driver under 21 (RCW 46.61.503) | At least 0.02, below the 46.61.502 level | Above 0.00, below the 46.61.502 level |
| Any driver, affected-by prong | No threshold - impairment is the test | No threshold |
Implied consent
RCW 46.20.308 is the implied consent statute: by driving in Washington, a person is deemed to have consented to a test of breath for alcohol, and in specified circumstances blood, when arrested on reasonable grounds for an impaired-driving offence. The officer must advise the driver of the consequences of refusal and of a test result above the thresholds.
RCW 46.20.3101 sets the administrative sanctions, and the exact figures matter:
| Situation | Sanction |
|---|---|
| First refusal within seven years, with no previous administrative action within seven years | Revocation or denial for one year - (1)(a) |
| Second or subsequent refusal within seven years, or a first refusal where there has been one or more previous incidents within seven years resulting in administrative action | Revocation or denial for two years or until the person reaches age 21, whichever is longer - (1)(b) |
| Test result 0.08 or more alcohol, or 5.00 or more THC - first incident within seven years | Suspension for 90 days, unless the person successfully completes or is enrolled in a pretrial 24/7 sobriety program - (2)(a) |
| Same - second or subsequent incident within seven years | Revocation or denial for two years - (2)(b) |
| Under 21, alcohol 0.02 or more or THC above 0.00 - first incident within seven years | Suspension or denial for 90 days - (3)(a) |
| Same - second or subsequent incident within seven years | Revocation or denial for one year or until the person reaches age 21, whichever is longer - (3)(b) |
Three corrections to widely circulated versions of this table:
- There is no three-year refusal tier. The ladder is one year, then two years; a third refusal is covered by the words "second or subsequent."
- The two-year refusal sanction has an age floor - two years or until 21, whichever is longer.
- The 90-day first-failure suspension has a 24/7 sobriety program exception added by 2020 c 330.
RCW 46.20.3101(4) gives day-for-day credit for any portion of a suspension or revocation already served under RCW 46.61.5055 arising out of the same incident, with no additional reissue fees where credit is full.
Ignition interlock
A driver whose licence is suspended or revoked for an impaired-driving matter may be eligible for an ignition interlock driver licence, which permits driving only in vehicles equipped with a certified ignition interlock device and requires proof of financial responsibility. Eligibility rules and required device periods change with legislation, so refer students and families to DOL for the current terms rather than stating a fixed period.
Teaching impairment to teenagers
Lead with the licence, not the criminal case. A 17-year-old finds "90 days without a licence" more concrete than "gross misdemeanor." Work the administrative table first.
Make the under-21 numbers vivid. 0.02 is reachable from a single drink for a small person. Above 0.00 THC means any detectable amount at all. The practical message is not "drink less" - it is "the legal exposure begins at a level you cannot feel."
Cover combination effects. RCW 46.61.502 reaches impairment "by a combination of" liquor, cannabis and any drug. Sub-threshold amounts of two substances can support the affected-by prong.
Include prescription and over-the-counter medication. "Any drug" includes lawfully prescribed ones. Antihistamines, sedatives and some pain medication all impair.
Include fatigue. Fatigue is not a DUI offence but produces comparable degradation in reaction time and lane keeping, and it is a required curriculum topic under the driver behaviour and driver attention standards.
Tie it back to the IDL sanction ladder. Under RCW 46.20.075(1)(g), an alcohol or drug adjudication during the permit period bars an intermediate licence outright, and under RCW 46.20.267 a chapter 46.61 RCW conviction is a strike on the three-step ladder.
Use Washington data. Target Zero identifies impairment as a growing contributor to Washington's fatality trend, and state numbers land harder than national ones.
[!WARNING] Exam traps in this section
- 0.08 alcohol and 5.00 THC are the adult per se levels; 0.02 and above 0.00 are the under-21 levels.
- The affected-by prong has no threshold.
- Refusal: one year, then two years or until 21 - there is no three-year tier.
- First test failure is 90 days, subject to the 24/7 sobriety program exception.
- Under-21 second incident: one year or until 21, whichever is longer.
- Both prongs are measured within two hours after driving.
A 19-year-old driver's blood test returns an alcohol concentration of 0.03 within two hours of driving. Which statute applies and what is the offence class?
Under RCW 46.20.3101(1), what administrative sanction applies to a second refusal of a breath or blood test within seven years?
What are Washington's per se thresholds for driving under the influence under RCW 46.61.502, measured within two hours after driving?