In State v. Arreola (pdf), the Washington Supreme Court confronted, once again, the tension between liberty and privacy interests and safety and security intersts.  There, it ruled that a police officer may conduct a traffic stop to investigate unlawful activity (driving under the influence) without any permissible basis for doing so as long as there is another – independent and lawfully sufficient – reason for the stop.  As Justice Chambers notes in dissent, the majority’s holding does not appear to comport with existing case law or with the constitutional mandate that “no person shall be disturbed in his private affairs … without authority of law.”


On October 10, 2009, Officer Tony Valdivia responded to a report of a possible DUI in progress.  He located a vehicle matching the description provided and followed the vehicle for approximately 30-45 seconds.  During that time, Officer Valdivia did not observe any signs of intoxicated driving, but did notice an altered exhaust in violation of RCW 46.37.390.  He therefore activated his overhead lights and pulled over the car.  Officer Valdivia admitted that his primary motivation for doing so was to investigate the reported DUI, and in fact the driver was intoxicated and arrested for driving under the influence.  Officer Valdivia further testified that the muffler violation was also “an actual reason for the stop” and that he “would have stopped the vehicle, once following it, even if he wasn’t suspicious of a DUI.” 

The issue on appeal was whether the stop was constitutional.  The court of appeals concluded that it was not constitutional and reversed the trial court’s contrary ruling.  The Supreme Court granted review and agreed with the trial court.


  • Article I, section 7 of the Washington Constitution protects the “private affairs” of each person from disturbance imposed without “authority of law.”  It is grounded in a broad right to privacy and the need for legal authorization to disturb that right.
  • Warrantless disturbances of private affairs are subject to a high degree of scrutiny.  As such, a warrantless traffic stop is constitutional only if it is based upon a reasonable articulable suspicion of either criminal activity or a traffic infraction.
  • Warrantless traffic stops are allowed only because such stops are reasonably necessary to enforce traffic regulations and to further the governmental interest in traffic safety and the general welfare.
  • Pretextual traffic stops are unconstitutional under article I, section 7.  Such a stop occurs when a police officer relies on some legal authorization as “a mere pretext to dispense with a warrant.” 
  • Addressing the issue on review – a so-called “mixed-motive traffic stop” – a traffic stop is not unconstitutionally pretextual so long as the officer can reasonably articulate an actual, conscious, and independent cause of the stop. 
  • Here, Officer Valdivia testified that he made a conscious decision to pull over the vehicle for the muffler violation.  Because the suspected infraction was an actual, conscious, and independent cause of the stop, it was not pretextual.


Justice Tom Chambers (joined by Justice Debra Stephens) dissented.  Officer Valdivia admitted that his primary reason for stopping the car was to conduct a speculative criminal investigation – that is, to check for intoxication despite having no constitutionally permissible basis for doing so.  Because the primary reason for the stop was unconstitutional, it does not comport with article I, section 7 of the Washington Constitution.