NILES, Mich. (AP) — Michigan State Police officers are conducting roadside saliva tests on suspected drug-impaired motorists as part of a program spurring questions about the tests’ accuracy.

State Police Special First Lt. Jim Flegel tells the South Bend Tribune that the program uses a portable saliva-testing device that can tell officers if a driver has certain drugs in his system, such as marijuana or opiates.

Michigan Medical Marijuana Association president Michael Komorn says he’s concerned about the tests’ accuracy and the program’s experimental nature.

The $150,000 program is called the Preliminary Oral Fluid Analysis. Flegel says it aims to combat an increase in fatal crashes caused by drug-impaired drivers. He says officers must have a reason to suspect impairment before testing a driver.

The program is currently being used in five Michigan counties: Berrien, Delta, Kent, St. Clair and Washtenaw.