Can an unmarked patrol car pull you over in WA? What WSP policy, state law say

If you drive on I-5 regularly, chances are you’ve seen the speed of traffic suddenly drop below the speed limit, only for a white patrol car to come into view on the shoulder.

Oftentimes, drivers going above the speed limit can see a patrol car and slow down before getting pulled over. But what if the patrol car isn’t marked?

Some law enforcement agencies use unmarked police cars to observe the roads without alerting drivers that they’re being watched by an officer.

As the summer months approach — when fatal crashes involving speeding drivers are most likely according to the Washington Traffic Safety Commission — here’s what to know about the use of unmarked police cars in Washington state.

Does WA state law allow unmarked police cars?

Under state law, any publicly-owned car has to display the name of the city or state agency operating them “in letters of contrasting color not less than one and one-quarter inches in height in a conspicuous place on the right and left sides thereof.”

The law makes a few exceptions, though. One is for public transit and another is for cars on loan to a school district.

Then there are two exceptions carved out specifically for law enforcement agencies. One is for any “sheriff’s office, local police department, or any vehicles used by local peace officers under public authority” while the other is for the Washington State Patrol.

Those exceptions allow law enforcement agencies to use unmarked cars “for special undercover or confidential investigative purposes.”

WSP unmarked car program

WSP maintains an entire fleet of unmarked cars. According to Sergeant Jermaine Walker, WSP’s director of media development, there are currently 50 cars in the program, called the Aggressive Driving Apprehension Team.

“This team is comprised of 50 vehicles in various colors, with no decal markings and interior or hidden emergency lighting,” Walker told McClatchy in an email. “These vehicles are also equipped with normal license plates to blend into traffic.”

That includes the unmarked patrol car that’s circulated online in the Seattle area with a bumper sticker reading “Please be patient, new driver,” according to reporting by KING5.

According to Walker, these cars can be found across the state, although there are more of them in heavily populated areas.

“Every district has ADAT troopers assigned, and the number of ADAT troopers assigned to a specific district is based on population and traffic flow,” Walker said.

According to WSP’s website, ADAT was launched in 1998 with two unmarked cars in an effort to take proactive measures against aggressive driving. By 2004, the team was operating 33 unmarked patrol cars, according to a 2004 article by then-WSP Chief Lowell Porter in the law-enforcement industry journal.

Can an unmarked car pull you over for speeding?

Walker said that the purpose of the unmarked cars is “to reduce collision-causing violations by identifying and intervening in aggressive driving behavior.”

But if you’re driving a few miles an hour over the speed limit, can you get pulled over by an unmarked car, or do ADAT officers focus on aggressive driving like the name suggests?

According to Walker, officers in unmarked patrol cars have the same powers as those in marked cars.

“These troopers have the same police powers and abilities as all troopers,” Walker said. “They will respond to 911 calls and intervene in everyday violations they observe, such as troopers in fully marked patrol cars.”

However, that doesn’t necessarily mean ADAT officers are looking for any reason to pull over unsuspecting drivers. In a 2016 video on WSP’s YouTube page, Trooper Josh Sanborn said that ADAT is primarily looking for drivers committing blatant traffic violations.

“We’re looking for the people that are doing the 20-plus over miles an hour. But we’re also looking for those unsafe lane changes, cutting people off, weaving in and out of traffic, following too close, tailgating… We’re looking for just those people that are more likely to cause a collision and get them to change their behavior,” Sanborn said in the video.

This story was originally published May 29, 2025 at 5:00 AM with the headline "Can an unmarked patrol car pull you over in WA? What WSP policy, state law say."