Comment Re:Participation not exactly "voluntary"... (Score 2) 562
California has mobile SMOG checks that are also "voluntary". Vehicles are flagged out of traffic by a CHP officer, at which point you're allowed to choose whether you want to have your car smogged. Although if you refuse to have your car checked, your license plate is recorded and logged for later analysis.
-Section 4.3
"The license plate numbers of vehicles whose operators decline to participate in the Roadside Inspection Program are recorded and entered into a laptop computer for later analysis."