My libertarian philosophy still applies as follows:
We have always had laws against drunk/impaired driving. This does not end with libertarianism. You have the right to get drunk and blow your hand off with fireworks but that doesn't excuse you when you burn your neighbor's house down. You have just crossed the line between your freedoms and my property. Don't expect me to sew your hand back on, either or pay to for the hospital stay.
No-one should tell me who I can barter with or sell my crops to as long as it is between myself and another adult. Whether or not I give a bushel of tomatoes or a bag of pot to an adult neighbor in exchange for his beer or a beef shoulder is between the two of us. If I trade my tractor to a friend for his horses, that's our business. Since public market trading for profit using
legal tender money is taxable, then and only then does this become the business of the government and give them control over anyone's business. They do print the money so you give them that option when you choose that route. As adults, it is our responsibility to take reasonable means to ensure that our property is not used for evil purposes.
A car, truck, tractor, gun, ammunition, beer and the marijuana all have the potential to kill someone. Killing is a criminal act. No one should hold Ford responsible when some nigger gets drunk and high as balls then decides to use his gun and truck to rob a bank, run from the police, and crash into a school bus.
As far as the more complicated chemicals, I'm not saying we should all go breaking bad here. Obviously, lines have to be drawn and they have been complicated by the market's pursuit of street drug profits since the war on drugs began. It should rightly be called the war on behavior and it was brought about due to weak individuals whose refusal to self discipline and avoid addictive bad behaviors brought us all the loss of liberties we previously enjoyed. Most people don't realize how post revolution China solved the opium den problem. Dealers were executed immediately. Free rehab programs were offered to everyone during a grace period. If you got caught after that, you were executed as well. Talk about the other end of the spectrum, huh...
The thing about pure libertarian governing is that it only works as our Constitution designed it to work with a certain peculiar people.