So far as has been reported then 5 pilots have been tested, and 3 failed. That's 60% fail.
BALPA can try to make Police act is a SOP in that area, but BALPA don't make the decision, the police officer does. In any event is it right that a union should dictate what a police officer can and cannot do?
Sorry to say this, but welcome to the real world, where people do ring police about many things, some real, some not.