The police can do that - however, they need reasonable suspicion for it. I have refused to be tested for alcohol successfully in the past. I didn't drink anything, I just don't like such tests being routinely used when there is no indication that alcohol or drugs were consumed.
I wonder if that only works on checkpoints/ places where masses of vehicle get checked, I don't think it would work if you the only one getting pulled out(atleast ime in Baden-Württemberg), drinking suspicions haven't been more than "have u had smth to drink? "+l and if suspicion is high enough a "where have you been/where you going to ", never breathalyzers
But cannabis, wrong hair style+ couple younger people in car= did u smoke? "No "well we will make sure of that ourself"
