The American Civil Liberties Union filed a federal class-action lawsuit Thursday against the Kansas Highway Patrol alleging troopers of targeting with unconstitutional detention motorists with out-of-state license plates or traveling to or from the recreational marijuana state of Colorado.

ACLU attorneys asserted KHP troopers relied upon an approach to motorists referred to as the "Kansas Two Step." It involves unlawfully detaining drivers with questions about travel plans without consent or reasonable suspicion of criminal activity after the initial purpose of the stop was resolved, the lawsuit said.

Lauren Bonds, legal director for ACLU of Kansas, said the "two step" had been relied on to expose detained motorists to canine unit searches and personal pat downs at the side of the road. The lawsuit was filed on behalf of three plaintiffs stopped by KHP.

"This practice is unconstitutional on many levels," she said.

KHP Lt. Adam Winters said the state law enforcement wouldn't comment on pending litigation.

The ACLU alleges the maneuver at the root of the lawsuit became a standard tactic of troopers who issue a ticket or warning, tell the driver to have a safe trip, take a couple steps toward a patrol vehicle but return to the driver's window to ask if the motorist would be willing to answer more questions.

This technique taught to KHP officers and incorporated in the agency's training materials is designed to break off the initial traffic detention and re-engage the driver in what could be interpreted as a separate consensual encounter, the ACLU alleged.

"KHP troopers will detain drivers based on innocent-travel indicia for this type of non-consensual questioning after the original purpose of the traffic stop has dissipated," the lawsuit said.

Absent intervention by the courts, the ACLU said, plaintiffs Blaine Shaw, Samuel Shaw and Joshua Bosire fear they would endure continued unlawful detentions while traveling to what law enforcement officials consider a drug-source state.

Documents filed in U.S. District Court by the ACLU alleged 96% of the KHP's civil asset forfeitures in 2019 involved out-of-state motorists driving on Interstate 70. Drivers with out-of-state plates comprised 93% of KHP traffic stops during 2017, the suit said.

"The standard for this kind of invasion of privacy has to be higher than out-of-state plates, a Colorado destination and minority status," Bonds said.

In 2016, according to the complaint, the 10 U.S. Circuit Court of Appeals found in Lewis v. Vasquez that KHP troopers had illegally relied on the fact that a driver was traveling from Colorado and other innocuous conduct to support their “reasonable suspicion” that the driver was trafficking drugs.