Zero tolerance policies are the traditional default response to rising drug problems. The rationale is that by cracking down on even minor drug offenses, applying severe penalties, and letting everyone know you’re not fooling around, others will be deterred from drug use.

It sounds great on the campaign trail, but in practice, it’s often a failure. Here are just three reasons:

For one thing, it’s probably too late. Drug epidemics start small and escalate. They sneak up on us. They’re well underway before we get around to doing something. They can be like closing the barn door a week after the horses escaped.

Take the cocaine epidemic. The US had a system in place to track emerging drug use patterns. For a variety of reasons, it simply didn’t work for cocaine use. The data was wildly inaccurate. There were already millions, not thousands, of cocaine users. As the calls rolled into his 800-Cocaine hotline, founder Mark Gold shared this information with the government. The response: They revised their estimates upwards.

Then there’s the matter of secondary gain. There’s so much money in drugs, legal and illegal, that people work hard to protect their income. They resist attempts to reduce sales. Sometimes “they” are professional criminals. Sometimes “they” are executives in office suites.

Take the prescription painkiller epidemic. Industry lobbying stymied intervention. Marketing campaigns aggressively sold opioids to gullible audiences. By the time people in healthcare woke to what was happening, “pill mills” were already flooding communities with synthetic opioids. Many of those pills wound up on the streets. Frantic efforts to restrict access to these prescription meds actually pushed users towards street heroin.

Zero tolerance? A bit late, don’t you think?

Another problem: In the world of zero tolerance, society arrests and incarcerates vast numbers of people. Where do we put them? Jails are already overcrowded. We could build more jails, of course, which would make some private prison investors very happy. But our nation already leads the developed world in incarcerating people, partly because of our love affair with zero tolerance.

And as one jurist explained, no matter how many jails we build, without viable alternatives, the Courts will simply fill them. And look around for more.

But jail is expensive and besides, eventually people get released. What’s changed for them? Little or nothing. A former inmate put it this way: “I can jail standing on my head. It’s the outside world that gives me fits.”

I suspect that zero tolerance policies are a fond fantasy that society returns to every so often, if only to learn, once again, why they aren’t effective. There are better approaches out there, if people bothered to look.