Illegal drugs are available everywhere. They're even available in prisons.

If you can't even keep them out of prisons, how effective do you think making them illegal has been on availability?

I feel this is a very important point. Legality appears to have little effect on usage. All we really do is apply another label to a user/abuser; that of a "criminal".

If the aim is to reduce the social problems caused by addiction then criminalization is the wrong way to do it.

Now addicts are 'taken care' by the justice system which is less effective and more expensive than social and healthcare programs would be if applied to the same population.