DETROIT (AP) — Medical marijuana patient fees are helping finance aggressive enforcement efforts in the Detroit area, where local sheriff’s departments spent over $600,000 in Michigan grant funding.

Law enforcement officials tell The Detroit News the grants have helped them crack down on criminals operating outside the law. Departments have used the money for overtime pay, raid gear, dispensary stakeouts and vehicles used to haul contraband pot.

Legislators created the grant program two years ago, permitting sheriffs to use extra money that had accumulated in the state’s medical marijuana fund for enforcement, education or communication related to the 2008 law approved by voters.

The program’s opponents say it’s wrong for the state to use mandatory patient and caregiver registration fees to perpetuate a “war on drugs” that can trap the same patients who are supposed to be protected.