The notion of deterring drug users with criminal sanctions is quite silly. Of course most drug policy actually concentrates on the supply side rather than demand side, but the argument I’m about to make applies to both kinds of drug control policy. Supply interdiction raises the cost of obtaining drugs by raising the price the buyer pays for those drugs (both the monetary price and the time “price” imposed by searching for a product in a black market). Sanctions against the users themselves increases the price by threatening users with police harassment or jail time (possibly including violent forced-entry raids on residences and the removal of children from a parent’s care).
Consider the price that a user pays for their drugs, first in the absence and then in the presence of prohibition. This will be an all-inclusive price, not just the money paid for the drugs. It will include the money, the time spent acquiring and using the drugs, and the various risks inherent to drug use (overdose, social disapproval, risk of losing control and committing a crime under the influence, etc.). Measure it in whatever units you like for whatever quantity of drugs you wish to consider, and call it X. Maybe X is “a 1% chance of completely ruining your life” or “20 hours of labor” or “$1,000”. It doesn’t really matter what units we’re using; we just want some number that we can compare to some other number. X will stand for the price of drugs in the absence of prohibition, and Y will stand for the price of drugs in a regime of fairly strict drug prohibition (as the United States currently has).
Y is greater than X. That is the point. That is how drug prohibition works. Increase the cost of using drugs, and (presumably) people use less of them. But that is not nearly enough. You must weigh the “benefits” of decreased drug use against the costs of the drug prohibition regime. That is what goes missing in the vast majority of commentaries on drug prohibition. It doesn’t count as success to merely decrease the number of users. To declare “success” you must achieve this end (with quantified and well-accounted for benefits of such a reduction) at an acceptable cost. I’m arguing here that “success” is implausible.
Suppose a not-unreasonable relationship between price and consumption such that doubling X cuts in half the amount of drug use. (And a tripling cuts it to a third, and a 1.2-fold increase cuts it to 1/1.2, and a tenfold increase cuts it to 1/10, and a Z-fold increase cuts it to 1/Z.) A prohibition regime increases the price from X to 2X and cuts the number of users in half. But those users each bear twice the cost, so the total harm is the same. (Actually greater, because we haven’t factored in the cost of the resources used to fight the drug war.) It doesn’t do you any good to say, “Well, increase the cost the user faces to 3X, or 10X!” You get the same answer: less drug use, but a much greater cost per user. This is a dubious goal anyway, considering that most people are actually risk averse. (Risk aversion means we’d rather face a high probability of a smaller cost than a smaller probability of a larger cost, assuming the average cost stays the same in both options.)
Maybe the scaling relationship is different, but it can’t be all that radically different. It might be a useful exercise to see how much the cost-benefit trade-off changes if, say, a Z-fold increase in price results in a Z^(1.5)-fold decrease in use rates. But first two caveats. 1) You don’t get to propose something implausible (like a Z^5 scaling law or some other extreme relationship). And 2) your proposed relationship must be consistent with empirical estimates of “elasticity”. Demand for drugs is actually highly *inelastic*, so the real relationship is probably more like a Z^(0.5) or Z-raised-to-some-other-fraction-less-than-one scaling law, such that doubling the price gets you *less* than a halving of drug use.
The enterprise of drug prohibition looks implausible on a cursory analysis. An absolutely thorough analysis would explicitly draw supply and demand curves and measure consumer and producer surpluses per those neat Economics 101 diagrams, but my overall point will stand. You might achieve a small deterrence at a small cost, or a moderate deterrent at a moderate cost, or a great deterrence at a great cost. But the cost of drug prohibition scales at least as fast as the benefit, and most likely (injecting what is known about the inelasticity of drug demand) faster. We don’t get an enormous benefit just by declaring drugs illegal. It’s not an on-off switch that we can simply switch to “off.” It’s a throttle. It’s a continuously adjustable lever. If drug warriors are hoping to achieve a large deterrent effect at a low cost, they are deluding themselves. To convince someone to stop using, you can’t just wag your finger and say “No.” To achieve real deterrence, you must pre-commit to some form of harsh punishment (comparable in harshness to the inherent dangers of the drug itself). Some people will continue to use, which means you must pre-commit to tracking down those individuals and carrying out the horrible punishment.
Let me give a little flavor to what I’m talking about. Phrases like “cost-benefit analysis” and “raising the price from X to Y” sound a little dry and technocratic. The real-world consequences of drug prohibition are soul-wrenching. “Raising the cost from X to Y” involves forcibly removing children from their parents, throwing victimless drug users into prison with hardened criminals, subjecting intravenous drug users to the dangers of wildly varying heroin potency and unknown adulterants (like fentanyl), denying those same IV drug users clean needles (subjecting them to an epidemic of blood-borne pathogens), harassing dozens of innocent motorists or pedestrians for each “guilty” one, denying sick people the only medicine that makes them feel well, and (let’s not forget) denying a perfectly safe thrill to those drug users who never cause any harm to themselves or others. That’s hardly a full list of the negative consequences of drug prohibition. I could go on for pages, but you get the point. Inject some humanity back into the above calculus, and the war on drugs isn’t just contradicted by some dry cost-benefit analysis. It’s unconscionable. It’s a moral abomination. Given that there are perfectly serviceable alternative policies, often referred to as “harm reduction,” our current prohibition regime is particularly wicked and foolish. It’s time to try something else.