[Turbo_pro]

Claiming that criminality does not deter use is like saying, we don't need speed limits because people speed anyway.
You may want to argue that punishment should fit the crime but that is a value judgment for society to make.

Society must set limits. We do this with standards and laws. Society suffers when one of it's members suffers. For society to encourage/approve of a behavior that is detrimental to any member is self destructive.

I guarantee you that if drugs were legal during my drug use days that the use by me and my acquaintances would have increased.