This is not the role of the police. Their role is solely punishment and deterrence.

And if drug use leads to other crimes and other crimes leads to punishment then they're already providing that deterrent, to the thing we actually want to deter.

If you want to prevent drug abuse in response to economic woes etc. then try building more housing and otherwise lowering the cost of living. (Sometimes people hate this because it's very "everything is connected" and they don't want to have to solve somebody else's problem in order to solve their problem, but sometimes that's actually the best solution.)

> BTW, if it's a crime to use certain drugs, and you use those drugs and are arrested, and that arrest prevents further crimes, this was NOT an example of "pre-crime". You committed a crime. You used illegal drugs.

Passing a law against drug use is pre-crime when the only real justification for the law is to prevent other crimes.