Earlier this year, one of the world's leading drug policy experts started an insightful, new paper in a very strange way, writing, "This paper is wrong. I hope it is nonetheless useful."

Jon Caulkins, of Carnegie Mellon University, immediately acknowledged that he was trying to predict the future. But this was necessary. After all, he was trying to tackle a question that's at the heart of drug policy today: How, exactly, will the war on drugs end, if all the doomsayers are right?

By now, everyone who remotely follows drug policy has heard the refrain: The war on drugs is doomed. It's been called a failure time and time again — by liberals like Bernie Sanders and conservatives like Chris Christie. It's been blamed for mass incarceration, gun violence, and chaos around the world. Prominent billionaires have thrown their weight behind ending the war on drugs. Even America's drug czar, arguably the world's leader in the war on drugs, has characterized the "old war on drugs" as "failed policies and failed practices" of the past.

But it's hard to imagine moving from a world where drugs are totally illegal to one where some form of cocaine or opium is available for recreational use at your local CVS. And it's harder to imagine just about any major US politician advocating for moving in that direction.

It's hard to imagine moving from a world where drugs are totally illegal to one where some form of cocaine or opium is available at your local CVS

Caulkins's paper makes a big prediction: The final push won't start in the US or, indeed, any of the developed countries in which many lawmakers and drug policy experts believe the war on drugs, despite its serious flaws, has been a net good. After all, these countries have led the charge for stricter and stricter anti-drug efforts since the Hague International Opium Convention of 1912 — they don't look poised to pull all of that back anytime soon.

Instead, Caulkins argued the more likely option is that a Latin American country, saddled with almost no benefits from the drug war yet all the violence it entails, will push to end its own drug war — and even legalize currently illicit substances like cocaine. And in an increasingly globalized world, one country's decision to allow a brand new legal market for cocaine could lead to enormous consequences. How could the US, after all, even hope to slow the flow of cocaine if it's legal directly south of its border?

This is how the drug war could end. Not with a push from the developed nations that rallied the world into a global effort against drugs. But with a stand by the developing nations that have dealt with the brunt of the drug war's costs and none of its benefits — and the domino effect that follows.

Why the US most likely won't be the first to end the drug war

Doomed or not, the US most likely won't be the first country to end the drug war. That's for one reason: Federal officials and many policy experts widely agree that prohibition has been a net benefit to the US, despite some of its very serious costs.

"It's not in our interest to legalize," Caulkins told me. "Because the benefits the US gets from having the drugs be less available, not advertised, more expensive outweigh the costs for us of crime and violence and corruption in our own borders."

Yes, the drug war helped contribute to mass incarceration — although not as much as you might think, since fewer than one in five prisoners are in for drug offenses. Yes, the black market for drugs gives criminal organizations something to fight over — around 2,000 homicides each year in the US are gang-related, many fueled by drug violence. Yes, the drug war has been used time and time again to erode civil liberties — from allowing more wiretaps to civil forfeiture. And, yes, there are racial disparities in anti-drug enforcement — black Americans are more likely to be incarcerated for drugs even though they don't use or sell drugs at higher rates.

But the drug war has arguably kept drugs costlier and less accessible than they would be otherwise. This is the primary goal of the supply-focused, preventive side of the war on drugs: By targeting the supply of illegal drugs, the drug war makes these substances less accessible by driving up costs and preventing sales at fully legal establishments. The demand side of the drug war, meanwhile, focuses on treating and rehabilitating drug users after they exhibit signs of a serious drug problem.

"The benefits the US gets from having the drugs be less available, not advertised, more expensive outweigh the costs for us"

According to Caulkins's research, prohibition has made drugs more expensive and less accessible than they would be if they were legal. Fundamentally, the most popular illegal drugs are just crops — marijuana, cocaine, and heroin all come from plants. So there's really no reason these drugs should cost any more to produce than, say, coffee or tea. Yet throughout the distribution chain, the price of a single serving of coffee increases by roughly 635 percent. By contrast, because of prohibition, Caulkins said, cocaine increases by 6,427 percent, marijuana by 1,047 percent, and heroin by 3,745 percent through the chain. So the drug war has not eliminated drug use, but high prices have probably suppressed drug use versus the rates if drugs were legal.

Others may evaluate the costs and benefits differently for the US. As it stands, more than 20,000 people died of illegal drug overdoses in the US in 2013. Caulkins estimated that legalizing hard drugs could increase use by as much as 200 percent, which would lead to more drug abuse and deaths. Whether preventing that is potentially worth more violence over the black market for drugs, the erosion of civil liberties, bigger racial disparities in the criminal justice system, and more incarceration in the US is by and large a personal, philosophical call.

But federal officials and drug policy experts like Caulkins agree the drug war is worth the costs, at least for the US.

One point of caution: Even if prohibition currently prevents drug use, there's a very strong argument that the drug war is too punitive. A 2014 study from Peter Reuter at the University of Maryland and Harold Pollack at the University of Chicago found there's no good evidence that tougher punishments or harsher supply-elimination efforts do a better job pushing down access to drugs and substance abuse than lighter penalties. So increasing punishment or crop eradication efforts may not do much, if anything, to slow the flow of drugs.

Instead, most of the reduction in accessibility from the drug war appears to be a result of the simple fact that drugs are illegal, which by itself makes drugs more expensive and less accessible by eliminating avenues toward mass production and distribution.

How a Latin American country could render the drug war futile

Even though the drug war may be a success if you look at it solely from an American perspective, it is an absolute disaster for the Latin American countries in which drugs are produced for consumption by people in wealthy countries like the US. Because of this drug trade, many Latin American countries have been mired in horrific violence for decades. And that may make them prime candidates for taking the first step toward ending the drug war.

Take Mexico: After President Felipe Calderón stepped up his country's drug war in 2006, partly with the backing of the US-funded Merida Initiative, drug cartels didn't just go away. They fought back, leading to tremendous levels of violence. Public decapitations have become a particularly prominent tactic of ruthless drug cartels. As many as 80,000 people have died in the war. Tens of thousands of people have gone missing since 2007, including 43 students who vanished last year in a widely publicized case.

Drug cartels haven't inflicted such horrors by simply fighting the government and each other — they have also embedded themselves in government institutions through extortion, blackmail, and bribes. The 43 missing students, for instance, were killed with the apparent cooperation of a mayor and local police. So on top of increasing violence, the drug war appears to increase corruption within governments.

Drug cartels have embedded themselves in government institutions through extortion, blackmail, and bribes

To be clear, Mexico is not fighting the drug war just for itself. Drug use isn't particularly high in the country: National drug surveys show about 1.5 percent of Mexicans ages 12 to 65 in 2011 used illicit drugs in the previous year, compared with about 8.7 percent of all Americans 12 and older in the previous month in 2011. (The age and timespan differences are due to differing methodologies in national surveys, but they nonetheless show that way more Americans use drugs than Mexicans.)

Mexico is, instead, fighting a drug war — with US financial support — to stop the flow of drugs that mostly America and other wealthy nations consume. So Mexico is taking on all this violence to stop the flow of drugs into the US and other rich countries. And Mexico is not alone — it is widely understood that wealthier nations are the consumer countries, while developing nations like Colombia and Bolivia are merely the sources of production, and Mexico, much of Central America, and parts of Africa act as transshipment hubs in the drug trade.

As economists Daniel Mejia and Pascual Restrepo wrote in a 2014 paper, this scheme is not a trade-off that developed countries like the US would likely be willing to accept:

Suppose for a moment that all cocaine consumption in the US disappears and goes to Canada. Would the US authorities be willing to confront drug trafficking networks at the cost of seeing the homicide rate in cities such as Seattle go up from its current level of about five homicides per 100,000 individuals to a level close to 150 in order to prevent cocaine shipments from reaching Vancouver? If your answer to this question is 'perhaps not,' well… this is exactly what Colombia, Mexico and other Latin American countries have been doing over the last 20 years: implementing supply-reduction policies so that drugs don't reach consumer countries at the cost of very pronounced cycles of violence and political corruption, with the consequent losses of legitimacy of state institutions.

What's worse, as Mexico's experience suggests, trying to crack down on violence can cause even more problems. As Brookings Institution senior fellow Vanda Felbab-Brown explained in a 2014 paper, anti-drug efforts can cause the population to turn against government in situations in which, for instance, drug production and trafficking are the only source of jobs. And that disapproval can lead to more violence.

"A failure to actually provide such comprehensive alternative development — only promising it for the future and undertaking eradication prematurely — will result in social instability, critically destabilizing the government immediately after conflict," Felbab-Brown wrote. "In that case, the government will only be able to maintain eradication by resorting to very harsh measures toward the population and will have to maintain such repression for many years."

Many of these problems could be largely solved if governments built strong political, economic, and criminal justice institutions capable of dealing with powerful drug trafficking organizations. But this task is made much harder when governments are effectively waging a war against criminal groups — leading to enormous levels of violence that make any kind of meaningful institutional or economic buildup difficult, if not impossible. After all, who is going to start a business in a city where a drug cartel and the government are effectively waging war?

What's worse, these drug trafficking organizations can sustain themselves even while fighting big governments because the drug war makes drugs so expensive. According to Caulkins's research, a nearly pure gram of cocaine costs about $2.44 in Colombia, where it's produced — but climbs up to $175 per pure gram once it ends up on US streets. That enormous profit makes the risk of seizure and the costs of a bloody war against national governments worth it, from the perspective of a drug cartel.

Drug trafficking organizations can sustain themselves because the drug war makes drugs so expensive

These tremendous profits explain the "balloon effect": Since drugs are so lucrative, drug producers and traffickers don't just cease to exist when governments go after them; the business is so profitable that someone will always be there, willing to replace defunct organizations. So production and trafficking shift to other people and areas, spreading the drug trade and the violence that often comes with it. This has been documented time and time again — when drug trafficking moved from Peru and Bolivia to Colombia in the 1990s, the Netherlands Antilles to West Africa in the early 2000s, and Colombia and Mexico to El Salvador, Honduras, and Guatemala in the past decade.

An alternative to continuing the crackdown, then, is to legalize — move drugs from the black market to the legal market, removing an enormous source of revenue for criminal organizations. While this wouldn't vanquish criminal organizations, it could severely weaken them — and make them more manageable for countries with weak governmental institutions.

"At first [cartels] would try to do other business, but the fact is that there's nothing as profitable and easy to sell in the black market as drugs," Isaac Campos, a drug history professor at the University of Cincinnati, previously told me. "How much easier is it to move 2 kilos of cocaine, which are worth $50,000 or so, across the US border than it is to move $50,000 worth of assault rifles?"

All of this suggests that eventually some country in Latin America or Africa, tired of the abhorrent levels of violence caused by prohibition, will eventually try to legalize. And once that happens, the entire international drug control regime will be doomed.

Some country could eventually legalize — and make the drug war futile

Given the enormous problems caused by the drug war in Latin America, it's likely that eventually some country there will legalize to try to reduce levels of violence within its borders. (Some countries are already moving in this direction — see Uruguay's decision to fully legalize marijuana.)

It is hard to say how, exactly, this would play out. Caulkins's 2015 paper cautions that many of his predictions are guesswork.

But his paper, based on what we know about current markets and the stated interests of these countries, provides a persuasive perspective for what would happen if a Latin American country were to legalize. For one, legalization wouldn't necessarily stop even most drug-related violence within a country's borders. The source of demand for most drug trafficking comes from the US and other developed countries. So since consumer countries like the US would likely keep drugs illegal (at least at first) if a Latin American nation legalized, this demand for illegal trafficking would largely remain steady — fueling the violence for some time.

But drug legalization in a Latin American country could lead to a domino effect that eventually pushes developed countries like the US to relax their anti-drug laws.

So how would all of this play out? Caulkins argued that Bolivia is a likely candidate for the first country to act by legalizing cocaine over, say, Colombia. "Colombia is a big country with a diversified economy, so hosting a legal cocaine trade is something it can take or leave — it's got plenty of other things going on in its economy," he said. "Bolivia's economy is tiny, so hosting the legal cocaine industry in Bolivia could make a difference to it economically." (This could even be to Colombia's benefit, since it would move cocaine production to Bolivia, freeing Colombia of an illegal, violent market.)

"Once it's impossible to prevent the price collapse, then maybe at that point the United States might as well legalize"

This likely wouldn't have too much of an impact on trafficking countries like Mexico or Honduras, or consumer countries like the US — besides potentially making cocaine less expensive for trafficking groups. After all, Bolivia is so geographically separated from the US that the cocaine would still presumably have to run through the same route it does today, which means it would still have to run through countries where it's illegal.

(It could even be to the US's benefit if only Bolivia legalizes: If the country goes ahead with legalization, and it turns out that drug use doesn't spiral out of control, then that would suggest that legalization wouldn't be the end of the world and prohibition isn't worth the costs. But if Bolivia legalizes and drug use spirals out of control, that would provide a cautionary tale. Either way, a useful experiment for America.)

What could dramatically alter the global drug war is if a transshipment country like Mexico, fed up with rampant violence, were to follow Bolivia's example and legalize. That could suddenly make drugs much more accessible in the US and other consumer countries, since that would lead to big, legal markets in countries that are better suited to directly ship to America. If the US couldn't stop these shipments, Caulkins wrote, "the jig is up." The abundant flow of legal cocaine would drive prices down, potentially making prohibition — which is meant to keep drugs costly and therefore inaccessible — no longer worth the costs of more incarceration and higher levels of black market violence within the US.

"So now you've got cocaine selling for a dollar a gram across the border of the United States, so inside NAFTA," Caulkins told me. "At that point, it may just be a fait accompli, and there's really no way to prevent the price collapse. Once it's impossible to prevent the price collapse, then maybe at that point the United States might as well legalize."

That would push the US, as well as other consumer countries, to adapt. So what then?

The US may need to focus on treating drugs as a public health issue

If drugs become more accessible through countries that legalize, then it would likely make sense for the US to shift to treating currently illicit drugs more like it treats alcohol and particularly tobacco today. After all, the drug war's traditional supply-side approach would likely become futile once there were places legally mass producing and shipping psychoactive drugs around the world — there would simply be too much supply to prevent a price collapse.

The US could take some preventive measures. It could, for instance, legalize, regulate, and tax drugs that are currently illegal. Legalizing would likely drive down the price of drugs further, and it would certainly make them more accessible. But the US could take steps — high taxes, restrictions on which places can sell drugs, and so on — that would make the drugs relatively difficult to get while still making them safer to obtain than they would be in a completely unregulated black market.

But this approach has limits. If the US were to make drugs too inaccessible, it would likely give way to a gray market — one that deals with technically legal products, but in an illegal way. This is essentially what New York state has seen with tobacco: Since cigarette taxes are so high, many people smuggle cigarettes from other states to resell them in New York for marked-up prices that are still lower than the taxed prices. This is a big market in New York City in particular: As much as 60 percent of cigarettes sold in the five boroughs are untaxed.

"I don't know what the highest tax [for drugs] we could collect is," Caulkins said. "But I'm really skeptical that we could prevent the price decline."

The US could also step up education efforts, including awareness campaigns focused on harm reduction and even warning labels that make it very clear certain drugs are dangerous. Public health experts widely credit these types of efforts for bringing down rates of cigarette smoking, which plummeted, according to federal data, from 42.4 percent of US adults in 1965 to 19 percent in 2011.

The best approach may be for the US to step up its public health approach toward drugs

But the best approach may be for the US to step up its public health approach toward drugs. This is something that some developed countries are already doing. Portugal, for one, in 2001 decriminalized drugs and set up commissions that essentially connect addicts to treatment, as the European Monitoring Centre for Drugs and Drug Addiction explained in its report on Portugal's drug policies. So far, the approach has produced promising results: Drug-related deaths and HIV transmission rates — from needle use — are down. (An important distinction: Decriminalization removes criminal penalties for personal drug possession, but selling drugs remains illegal.)

Similarly, the US could decriminalize drug possession, keep the sales of drugs illegal, and expand drug abuse treatment programs. The US has actually engaged in some of this in recent years, with a greater focus on drug courts that try to put drug addicts into treatment instead of jail or prison.

But there are also plenty of untried ideas. Some places, for example, made heroin legally accessible in monitored facilities so addicts who don't see results from traditional treatments can use the drug in a safe environment without resorting to crime to purchase heroin. This approach has been credited with bringing down drug-related crimes in Switzerland in particular.

Some of the public health approach could even tap into the benefits of psychoactive drugs. As I've written before, there is a growing body of research that suggests powerful hallucinogens like LSD and magic mushrooms could be used for therapeutic effects that help people deal with anxiety, particularly about mortality and death.

Even these various approaches only touch on just a few of the ways the US could ease its drug war. The general point is that America would be pushed into a world in which drugs are legal, decriminalized, or, at the very least, much more accessible than they are today. And that could require policies that focus more on harm reduction, instead of trying to fruitlessly stop drugs, which would now be legal in other countries, from coming into the US.

Of course, all of this hinges on a lot of speculation about what the future of the drug war looks like. But given the struggles of many countries, particularly in Latin America, to deal with drug violence, Caulkins and other drug policy experts argue it's a very real possibility that this type of chain of events could play out in the coming decades. And that would mean the real end of the war on drugs as we know it.

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