Well, in that case no drug laws are needed, because there are already laws against bothering other people. (And if you do criminally bother others, it shouldn’t matter under the law whether you are on drugs or not.)
I would see nothing wrong with a law against e.g. shooting heroin in a public place. Even if people doing so were otherwise peaceful, if passersby were bothered that should justify police action. Absent such a law, I would see no basis for the police to take any action against someone peacefully shooting dope no matter how many people it offended.