Quote from Ghost of Cutten:
In that case, the undesirable activity is the breaking into peoples homes, stealing, defrauding the welfare system etc i.e. genuine crime. Which is already illegal. A bit like people who like alcohol but drink and drive, or drink and beat their wives or start fights. People who take drugs and *do not* commit crime (other than taking the drug of course) should be treated the same as people who drink and don't beat their wives, people who drink but don't drink and drive.
Basically you are convicting people who can take drugs without stealing or harming other people, for the actions of those drug-takers who do resort to crime and harm. On the same logic, we should convict everyone who drinks of a crime, for the actions of those drinkers who do commit crime whilst intoxicated. And convict all smokers, for the actions of those who smoke in front of their young children and fill their growing lungs with tar and carcinogens.
I take it you want to ban alcohol and smoking too, for those identical reasons right? After all, that is the only logically consistent position. Either you do collective punishment equally across all goods and acts which have negative social consequences (so cars are banned because some people drive recklessly and kill people; booze and cigarettes are banned etc), or you convict only on an individual basis, punishing people for genuine moral crimes that *they themselves have committed*. You don't jail people who have done nothing wrong, just because other people doing similar things decided to turn criminal.