I used to favor full legalization, but now I think it's a bad idea. If you can simply go to a store to buy heroin (like you can with weed in many places now), I think we will inevitably have more heroin addicts. People will get addicting just trying it out, and get addicted because they are self-medicating.

There are middle-grounds between full legalization and full prohibition. It seems obvious that prohibition has been a failure. I think instead we should base it on how harmful and addictive they are. Drugs with low harm and low addiction potential should be easy to get. Other drugs should be legally obtainable (and manufactured and distributed by legitimate means) by addicts, but hard to get for most people.

Sometimes people bring up the case of alcohol, which seems to have relatively high addiction potential and harm, yet is still legal. I think this is a case of path dependence though. I don't know if I would advocate making a similarly harmful drug legal and easily obtainable today, but the cat is out of the bag on that one.