Trick is, sincere belief in liberty includes belief in the liberty of dopers to shoot up.
Yup, a libertarian believes you are free to shoot up - anything you want, anytime you want.
What's the difference between a Libertarian who doesn't care if someone shots up, and a Conservative who doesn't care if someone drinks themselves into oblivion? They are both killing themselves - we both agree they have the 'right' to kill themselves. You seem to indicate that the 'medium' in which they kill themselves is important. A libertarian doesn't care what 'medium' they use; it's the philopshy that we each are responsible to make our own choices, that is important. I chose not to take drugs, this is my informed, adult and rationalized decision. You are free to do whatever you wish (with minimal criteria attached - adult, not killing innocents, children, etc).