Senate Bill 5664 amends multiple existing Washington statutes governing impaired operation of vehicles, vessels, and military conduct. The bill lowers the adult per se breath and blood alcohol concentration in RCW 46.61.502 and 46.61.504 (and related provisions) from 0.08 to 0.05 while keeping a per se blood THC threshold of 5.00 (specified in the bill as nanograms per milliliter of whole blood). It preserves the two‑hour measurement window for establishing per se violations and retains the affirmative defense that a defendant consumed alcohol or cannabis after driving, which must be proved by a preponderance of the evidence and given to the prosecution before omnibus or pretrial hearings. The bill makes a range of procedural and penalty changes rather than creating a new independent crime. It revises evidentiary and testing procedures (amending RCW 46.61.506 and RCW 46.20.308) by specifying breath and blood testing technical requirements, the state toxicologist’s permitting role, and warning and notice procedures for refusals. Administrative driver license actions are revised (temporary license rules, law‑enforcement reporting deadlines, seven‑day hearing request with a $375 fee subject to indigency waiver, hearing/appeal processes, and deferred prosecution stays). Sentencing and administrative penalties are adjusted: most violations remain gross misdemeanors but certain repeat or specified prior convictions trigger felony elevations (including class B or class C felony elevations under RCW 46.61.502(6) and 46.61.504(6)); RCW 46.61.5055 references an amended threshold changing a high‑BAC reference from 0.15 to 0.10. Courts are given explicit authority to order electronic home monitoring (EHM) or 24/7 sobriety monitoring in lieu of mandatory minimum jail in specified cases, to require ignition interlock devices, to impose non‑suspendable minimum fines or jail portions absent findings of indigence or serious health risk, and to require expanded substance use disorder assessments and treatment. The bill also amends related statutes: it lowers alcohol limits in the military code (RCW 38.38.760) and boating law (RCW 79A.60.040) to 0.05 and updates boating implied consent and offense classifications, directs the Washington Traffic Safety Commission to run a public information campaign, affirms that existing civil liability for commercial vendors is unchanged, and requires the Washington State Institute for Public Policy to evaluate the act and report to the Legislature by March 1, 2029. The act takes effect July 1, 2026. Several provisions and penalty details are incomplete or cut off in the provided text (including portions of RCW 46.61.5055 and other listed amendments), so the full scope of some sentencing ranges, subsection structures, and certain cross‑references cannot be confirmed from the extracted facts alone.

If enacted, the law would make it easier for prosecutors and licensing officials to act against drivers by lowering the adult per se blood/breath alcohol threshold from 0.08 to 0.05 while leaving the per se blood THC threshold at 5.00 ng/mL. That change, paired with detailed test admissibility standards and a two‑hour testing window, means more adult drivers could face administrative license suspensions, criminal charges, mandatory monitoring (electronic home monitoring, 24/7 sobriety), ignition interlock orders, and higher non‑suspendable fines in repeat or aggravating cases; courts can substitute monitoring for some mandatory jail time but offenders generally must pay monitoring device costs and may be required to undergo expanded substance use disorder assessment and treatment. The act also requires a statewide public information campaign and a Washington State Institute for Public Policy evaluation, and it takes effect July 1, 2026. The people and organizations most affected will be drivers (especially repeat offenders, those with child passengers, under‑21 drivers, and commercial drivers), courts, law enforcement, the Department of Licensing, counties/municipalities that set monitoring costs, and monitoring and treatment providers. Counties and cities may face higher demand to run or verify 24/7 programs and determine EHM pricing, courts must document decisions when suspending or converting mandatory minimums, law enforcement must meet stricter testing and reporting rules, and offenders will likely face greater out‑of‑pocket costs for monitoring, ignition interlocks, fines, and longer or more frequent license suspensions. Important details about some penalty schedules and certain amended subsections are truncated in the provided text, so the full scope of sentencing and some procedural specifics are not clear from these excerpts.