This bill amends Washington law governing driving under the influence by lowering the per se blood or breath alcohol concentration from 0.08 to 0.05 within two hours after driving or being in actual physical control, while maintaining a per se THC blood concentration of 5.00 nanograms per milliliter for adults. It creates specific under-21 per se limits (alcohol at least 0.02 but less than 0.05; any THC above 0.00) and defines driving under the influence to include alcohol, cannabis, drugs, or combinations. The bill allows blood or breath tests obtained more than two hours after driving to be used as evidence about concentrations within two hours and as evidence of impairment if above 0.00, and it provides an affirmative defense where a defendant may prove by a preponderance of the evidence that the intoxicant was consumed after driving, subject to pretrial notice requirements. The bill modifies criminal classifications, penalties, and administrative license procedures. It establishes varying misdemeanor and gross misdemeanor penalties (with specified minimum jail terms, fines, and alternative sentences such as electronic home monitoring and 24/7 sobriety program monitoring) that change based on number of prior offenses within seven years and on alcohol concentration (including different ranges for <0.15 and ≥0.15). Courts may substitute or suspend mandatory minimum confinement only with written findings and may require ignition interlock devices, alcohol monitoring, probation conditions, or expanded substance use disorder assessments and treatment where specified. Three or more prior offenses within 15 years can elevate punishment under chapter 9.94A RCW. The bill also amends administrative license actions: specified suspension and revocation periods for test results or refusals, hearing procedures and standards, stays for deferred prosecution in some cases, day-for-day credit for prior administrative action, and appellate review limited to the administrative record. The bill adds non-criminal provisions requiring a statewide public information campaign by the Washington traffic safety commission about the adjusted alcohol threshold and requiring the Washington State Institute for Public Policy to evaluate implementation impacts and report by October 1, 2027 (that evaluation provision expires November 1, 2028). The act takes effect July 1, 2026. Some statutory texts and cross-referenced amendments are incomplete or cut off in the provided material (including full language of RCW 46.61.5055, several subsection details, and certain probation conditions), so further specifics and complete penalty tables or exact procedural wording cannot be confirmed from the excerpts provided.

If enacted, more drivers — including adults — will face enforcement and sanction risk at a lower alcohol level because the per se blood/breath limit is reduced to 0.05, while THC per se remains at 5 ng/mL and under‑21 drivers face near zero‑tolerance (0.02 alcohol or any THC). Practically this means more arrests, more administrative license actions, and more court-ordered monitoring and treatment: courts are pushed toward using ignition interlocks, electronic home monitoring, or 24/7 sobriety programs (costs of monitoring generally fall to the offender and counties set those fees), expanded substance use assessments will be ordered more often, and fines and non‑suspendable minimums rise in many repeat or high‑BAC cases. Evidence and testing rules are tightened (specific breath test foundational requirements and limits on who may draw venous blood), defendants must give pretrial notice to assert post‑drive consumption defenses, and administrative hearing fees and timelines apply. The groups most affected will be drivers (especially repeat offenders and drivers under 21), law enforcement and prosecutors (more cases meeting per se thresholds and new evidentiary requirements), courts and treatment providers (greater demand for assessments and monitoring oversight), and monitoring/interlock vendors and counties (responsible for implementing and pricing programs). The traffic safety commission must run a statewide multilingual public education campaign and the Washington State Institute for Public Policy must study impacts and report by October 1, 2027; the act takes effect July 1, 2026. Some implementation details and parts of the penalty structure are missing from the provided text, so the full operational and fiscal effects on agencies and local governments cannot be determined from these excerpts alone.