What Is Probable Cause in Washington & Why It's the Foundation of Your Defense
You've probably heard the phrase on TV a hundred times: "We have probable cause." But in a real Washington criminal case, those two words carry enormous weight. Probable cause is the legal threshold police must meet before they can arrest you or search your property — and when they fall short of it, the evidence against you may not hold up.
What Does Probable Cause Mean?
Probable cause means an officer has good, fact-based reasons to believe it is probable that a crime was committed — and that you committed it, or that evidence of a crime will be found in a particular place. It doesn't require proof of guilt. But it does require more than a hunch, a gut feeling, or a vague suspicion.
For example, if a crime victim identifies you to police as the suspect, that alone can establish probable cause. An officer simply noticing that you look nervous generally cannot.
Probable Cause vs. Reasonable Suspicion
These two standards are often confused, and the difference matters.
Reasonable suspicion is a lower standard. It allows an officer to briefly stop and detain you — known as a Terry stop — if they can point to specific, articulable facts suggesting you may be involved in criminal activity. You are not free to leave during this kind of stop, but it is meant to be short and limited in scope.
Probable cause is the higher standard required to make an arrest or to obtain a search warrant from a judge.
In practice, a stop that begins with reasonable suspicion can only become an arrest if the officer develops probable cause along the way. If the facts never rose to that level, the arrest itself may be unlawful.
Where Probable Cause Shows Up in Your Case
Probable cause is not a single moment. It can be challenged at several points:
The traffic stop. An officer needs a legitimate reason to pull you over. Washington courts do not allow officers to use a minor traffic violation as a pretext to investigate something unrelated when they lack reasonable suspicion or probable cause for that other crime.
The arrest. Whether it's a DUI, assault, or drug charge, the officer must be able to point to facts that justified taking you into custody.
The search warrant. Before a judge signs a warrant, the officer submits a sworn statement explaining why they believe evidence will be found. If that statement is inaccurate, outdated, or too thin, the warrant itself can be challenged.
Why Washington Gives You Extra Protection
Washington's Constitution protects your "private affairs" under Article I, Section 7, and in many situations it provides stronger privacy protection than the federal Fourth Amendment. As we explained in our post on when police can search your car in Washington, warrantless searches are presumed unreasonable unless the State proves a narrow exception applies.
That burden often falls on the prosecution — and it's a burden many cases struggle to meet.
What Happens When There Was No Probable Cause?
If the stop, arrest, or search wasn't supported by probable cause, your attorney can file a motion to suppress. When granted, the evidence obtained as a result can't be used against you. Without that evidence, prosecutors may be forced to reduce the charges or dismiss the case entirely.
This is why a careful review of what happened before the evidence was found is one of the first steps in building a defense — whether you're facing a DUI, assault, or drug charge.
For a plain-language overview of these standards and your rights during a stop, see the Seattle Office of Police Accountability's Know Your Rights guide.
Think Your Rights Were Violated? Contact Verity Criminal Defense Today.
Not every arrest is a lawful one. At Verity Criminal Defense, we examine the details of every stop, search, and arrest to find out whether the police got it right — and we fight to hold them to the standard the law requires.
Free case reviews are available 24/7. We serve clients across King, Pierce, Snohomish, and Skagit counties, including Seattle, Bellevue, Tacoma, and Everett.
Give us a call or contact us online.