The bill amends existing Washington traffic and vehicle code provisions to lower the per se blood alcohol concentration for driving or actual physical control from 0.08 to 0.05 within two hours after driving or control, and to establish a per se THC blood concentration threshold of 5.00 within two hours. It preserves the separate “under the influence” impairment offenses and adds an affirmative defense allowing a defendant to try to prove by a preponderance of the evidence that post-driving consumption produced the measured level; defendants must notify the prosecution before the omnibus or pretrial hearing. Analyses taken more than two hours after driving may still be admitted as evidence that a person had a relevant concentration or was under the influence if any concentration above 0.00 is shown. The bill changes penalties and procedures across multiple statutes. Violations of RCW 46.61.502 (driving under the influence) and RCW 46.61.504 (actual physical control) remain generally gross misdemeanors but may be elevated to felonies for repeat offenders or certain prior convictions (class B felony under RCW 46.61.502 and class C felony under RCW 46.61.504 under specified prior-offense triggers). Courts gain explicit authority to impose or substitute periods of electronic home monitoring (EHM) or 24/7 sobriety monitoring for mandatory minimum imprisonment in specified cases, require ignition interlock devices and other alcohol/remote monitoring as conditions of sentence, and impose expanded substance use disorder assessments and treatment. The bill adds aggravating penalties for offenses committed with passengers under age 16 (additional interlock periods, jail days, and fines), revises license suspension/revocation/denial periods tied to the new 0.05/5.00 thresholds and test refusal, updates administrative hearing, appeal, and deferred-prosecution stay procedures for license actions, and amends rules for who may withdraw blood and the foundational requirements and admissibility standards for breath and blood testing. The act also extends the new thresholds to vessel operation and military code provisions, directs the traffic safety commission to develop a statewide public information campaign (multi‑media, multilingual, with hospitality stakeholder involvement and equity considerations), and directs the Washington State Institute for Public Policy to evaluate the act’s impacts and report by March 1, 2029. The act’s effective date is July 1, 2026. Several statutory amendments and subsections cited in the extracted text are incomplete or cut off (including parts of RCW 46.61.5055, multiple referenced subsections, the full text of new sections added to chapters 43.59, 66.44, and 66.08, and some penalty lists), and some cross-referenced definitions and agency identities are not fully specified in the available excerpts.

If enacted, more adult drivers will likely face automatic DUI enforcement because the per se alcohol limit is lowered from 0.08 to 0.05 and a specific THC blood threshold is set at 5.00 (measured within two hours). Practically, that means courts and law enforcement will see more cases meeting the automatic-test standard, which triggers mandatory consequences like ignition interlock installation for convicted drivers, administrative license suspensions or revocations, and expanded options for courts to require electronic home monitoring or 24/7 sobriety programs instead of some jail time. People convicted with child passengers face added jail, fines, and longer interlock periods. Offenders generally must pay monitoring and device costs set by the county or city, and agencies such as courts, the Department of Licensing, law enforcement, and county programs will have heavier workloads from new hearings, notifications, and record updates; commercial drivers, military codes, and vessel operators are also brought under the lower 0.05 standard. Those most affected are adult drivers whose measured alcohol or THC levels fall between the old and new per se thresholds, people who use cannabis, commercial drivers subject to disqualification rules, and local governments that set and collect monitoring fees. Costs shift toward offenders (monitoring, interlock, testing) while courts, the Department of Licensing, and monitoring providers face increased administrative and operational responsibility; the Washington Traffic Safety Commission must run a statewide public information campaign and the Washington State Institute for Public Policy must evaluate impacts and report by March 1, 2029. Some implementation details and penalty tables are incomplete in the provided text, so the exact scope of some fines, suspended sentence rules, and certain cross-referenced provisions are unclear.