Drugs should not be illegal. They can be restricted and I believe should, but I consider making the use of drugs a crime a terrible decision. Such policies could be made where addicts are given controlled doses of their drug in a controlled environment and given access to free help to fight their addiction.
In fact, I recently saw an article on the economist which talks about how this does in fact work to reduce addiction rates.
Policies like this are much more effective than putting people who need help in prison, and we should adopt them as soon as possible.