Don't know how long you've been riding in the area, But back a few yrs ago they tried this in caledon, mainly the forks. It was a hard time proving because of the conditions the test was administered, Had to be so far a way from obstructions of buildings and a few other procedures that had to be metconditions?
to my knowledge, depending on the municipality they only need suspicion to pull you over and administer the test.