I’m not opposed to all forms of drug prohibition. There are some forms that I like and that I believe to be necessary. But in those situations where prohibition is called for, it will virtually always be enforced privately. I’m not talking about some shadowy private security force doing armed SWAT raids on civilian residences looking for drug stashes (think Black Water, the private military company, or Lone Star Security from the game Shadowrun). I’m talking about boring everyday life making drug use an impossibility for most normal people.
Most people spend around half of their day in a restrictive institution of some sort. Most adults go to work. Most children go to school. Even outside of these environments, you may go to a store to do some shopping or go to a restaurant to eat. Many of these environments make drug-induced intoxication unfeasible. You could get drunk and go to work, but you’d most likely be found out and severely punished or, if it’s a repeat offense, almost surely fired. Likewise, if you go to a grocery store rambling incoherently and bothering the other customers, you will most likely get ushered out. Work and school are going to be far less forgiving than the restaurant or the store, but virtually everywhere you go there will be something constraining you from full-on drug intoxication. Even if we assume that workplaces and schools aren’t very good at spotting and punishing drug use, there are intrinsic penalties for these behaviors. Your work will suffer until you eventually get fired or kicked out of school, or at the very least you will not prosper as much as you otherwise could. Even if your boss is oblivious to your high-functioning alcoholism or your methamphetamine habit, if your work suffers your boss will eventually notice that.
Supposing your drug use doesn’t affect your work, there’s no cause for concern anyway as your habit isn’t causing a problem. If someone is very privately using intoxicants in a way that doesn’t affect their work or school, it’s hardly any of their concern. In this sense it’s unreasonable to do drug testing; your boss or school can observe your work product directly and decide whether it’s adequate. With the caveat that some drug use might have no observable effect on day-to-day work output but slightly raise the risk of a catastrophe (think an airline pilot using cocaine), directly observing someone’s work is the sensible solution. Testing for something that isn’t causing an obvious problem is a waste of time.
I can feel your objection welling up. “But…people do drugs anyway and ruin their lives. Clearly private deterrence is inadequate, right?” And to that I say, You’re missing the point. Yes, some people feel the bad consequences of their destructive drug habits. That is how incentives work. The people who behave irresponsibly are hurt by their irresponsibility. Observe that most people don’t have self-destructive drug habits. They see ahead of time that there is an enforcement mechanism in place and decide not to, say, smoke weed before reporting to work, or take heroin before sitting though a class lecture. Perhaps the negative consequences are so obvious that the idea of starting a drug habit doesn’t even occur to most people. It’s not a conscious decision not to smoke a bowl in the morning; the need to get your kids to school and get yourself to work rules that completely out of the question. For most people. And the guy who does try it goes to work smelling of their obvious habit, unable to focus, and gets punished or fired.
Perhaps I haven’t answered the objection fully. The argument is that government enforced prohibition enhances the already-existing (if sometimes tacit) private enforcement of drug prohibition. Does it make sense to go after those remaining screw-ups for whom the implicit penalties for drug use are inadequate? Not really. Not at all . It simply does not make sense to try to penalize people out of harming themselves, particularly when the demand for the drug is inelastic (as it must be for any self-destructive drug habit). The intuition here is that I have to harm you more than the drug harms you to get you to stop. Even admitting that a few potential drug users are deterred, the harm to the remaining users is so exacerbated that it doesn’t justify the costs. This is an outcome of very straightforward economic reasoning, requiring no actual grounding in economics or assumption of weird econ theorems or anything. A bit of logic alone will get you to this answer. Unless you posit some very strange, stilted assumption about how drug users respond to legal penalties much more strongly than implicit penalties (of comparable magnitude), you basically have to accept this conclusion: drug prohibition does more harm than good. It’s completely unnecessary. But such deterrence as everyday life naturally provides keeps most of us clean most of the time.
If you’re going to bring up harm to third parties (intoxicated motorists, neglected children, alienated friends, etc.), I answer that point here. In short, the externalities are 1) grossly exaggerated and 2) they are already internalized to the extent that the drug-induced misbehaviors are already illegal. I wish the prohibitionists would take their own arguments a little more seriously. My impression, having thought this through, is that they don’t really have a leg to stand on but they don’t have the patience to think the arguments through to their conclusions.