There should not be many justifications for this short of raid on private residences, and "small amounts of personal drugs" should not be one of them.
Bingo! Overkill may bring on the same sort of legalistic RoE crap that is preventing our soldiers from winning wars for fear of being imprisoned for killing an enemy disguised as a civilian. If cops can't police themselves, they will end up emasculating themselves and bringing about total anarchy, soon accompanied by tyranny.