Unfortunalty I have seen first hand these kind of dogs. Normally with the hoodies that deal drugs (old area I used to live in) a guy down the road used to teach his dog to hold onto trees for exactly that reason, but nothing could be done about it as he wasnt doing anything illegal
Its a sad fact that bull type breeds are targeted for use by these **** heads who are giving them the bad rep. And who suffers at the end only the poor dog

They should scrap all these crap ideas about muzzling dogs they should bring in a test that every dog owner should have to pass. If you cant produce a license (like a driving one) when stopped they should remove the dogs from your care until you either pass or sign the dog over. Would sort out a hell of a lot of problems IMO. If they can do it with cars they why not poor helpless animals