Participants in the CA Drug Recognition Evaluator Program (DRE) are reporting that they have been forced to participate in this testing or otherwise face arrest.
The California Highway Patrol's program is intended to train officers how to collect money for the state by helping to boost the prosecution of victimless crimes, *ahem*… identifying what substance a person is on, if any.
The first week of the training program the officers learn in a classroom setting. During the second week, the CHP has officers go out and target the struggling homeless population to coerce them into being subjects for officers to then practice on.
Unlike sobriety tests which are typically conducted on the roadside, DRE officers pick up anyone with probable cause, such as appearing intoxicated, carrying an open container, or pushing a shopping cart and bring them in to the DRE field testing program facility.