What would happen if America decriminalized prostitution?

It is difficult to answer this question definitively, but by now there has been a lot of empirical research on how decriminalization has worked in other countries and some places in the US.

So to get an answer, I reviewed dozens of studies, papers, and articles, and spoke to researchers about their work.

The evidence trended in one direction: Sex work should be decriminalized. It isn't a perfect policy — but the evidence suggests it's the best option, while prohibition doesn't appear to have good empirical evidence behind it.

I write that acknowledging that this is a contentious issue for a lot of people. Many people on both sides of the debate look at prostitution with preconceived notions. Critics of sex work, for example, may have already made up their minds that it is inherently exploitative, so it should be banned and eradicated at all costs. On the other side, advocates may see their opponents as misogynistic, because critics characterize sex workers as women who are incapable of deciding what to do with their own bodies. It's hard for these sides to find much common ground.

The research helps break through this debate — to examine how decriminalization would actually look. So here's what it says.

Decriminalization can improve public safety and health

The main argument in favor of decriminalization — that it can improve public safety and health, particularly that of sex workers — has been backed by some of the best research into prostitution.

A 2014 paper, published by the National Bureau of Economic Research, found that rates of rape and gonorrhea dropped dramatically after Rhode Island decriminalized indoor prostitution in 2003.

The study came after a surprising court ruling. A state court in 2003 ruled that an old law had decriminalized prostitution in Rhode Island, and it took until 2009 for state lawmakers to reinstate the ban. In the meantime, there was a 31 percent decrease in rape offenses and 39 percent fewer cases of female gonorrhea — and no extraordinary drop in other kinds of crime, suggesting the reduction in rape offenses was not representative of a broader crime drop or better policing across the board.

rates of rape and gonorrhea dropped dramatically after Rhode Island decriminalized indoor prostitution

The study said there was a likely explanation for the drop in gonorrhea cases: With the decriminalization of indoor prostitution, more of the industry moved indoors, which is generally safer than street prostitution since it tends to involve more condom use and less risky sex acts.

But researchers couldn't draw a definitive conclusion for the drop in rape, instead proposing a variety of theories. For one, decriminalization may give sex workers a better bargaining position relative to their clients — allowing them to seek help from employers and police should something go wrong. And decriminalizing sex work allows businesses to invest more money in security (locks, security cameras, security guards), and decreases the potential for police corruption (so cops are less likely to demand sex from a sex worker when a worker turns to them for help) — both of which could lower the incidence of rape.

There's also a more troubling explanation for the drop in rape offenses: Some violent men perhaps substituted rape with prostitution. The study found that the market for prostitution expanded following decriminalization. With more accessibility and no criminal penalty, would-be rapists may have shifted away from sexual violence and instead purchased sex. (Other research shows something similar happening with porn — in which some violent men substitute rape with porn.)

Some violent men perhaps substituted rape with prostitution

A 2015 study of decriminalization in the Netherlands, published by the Institute for the Study of Labor, produced strikingly similar results. In 1994, the Netherlands allowed cities to designate street prostitution legal in certain zones. In Dutch cities that did this, researchers found a 30 to 40 percent drop in sexual abuse and rape during the first two years. They also found evidence of long-term decreases in drug crimes, but no evidence of effects on other crimes, such as violent assaults and possession of illegal weapons.

"We conducted our study completely independently of knowledge of the [Rhode Island study]," Stephen Kastoryano, an empirical econometrics professor at the University of Mannheim and one of the Netherlands study's co-authors, said. "It's too much of a coincidence to not think about looking into more."

These types of studies show a clear benefit to decriminalization — not just to sex workers, but to public safety and health as a whole. And it's fairly convincing, showing the effects of decriminalization in very different places. In contrast, the research showing the potential downsides of decriminalization is very weak.

The anti-decriminalization research is hugely flawed

The prominent argument against decriminalization is that it will lead to more sex trafficking as the market and demand for prostitution grows. Unlike other arguments against decriminalization, which tend to focus on morality, this point poses an empirical question — and proponents of this view often cite studies that suggest decriminalization leads to more trafficking.

But the research on the connection between legal sex work and human trafficking is very flawed. Both issues are inherently difficult to study, since they're mostly illegal activities. But anti-decriminalization advocates often cite research that makes incredibly basic mistakes.

The research, for instance, often conflates human trafficking with sex trafficking. But sex trafficking is a subset of all human trafficking; human trafficking is the coerced movement or exploitation of people for any labor — from beauty salons to fishing boats — while sex trafficking is a much narrower criminal act focused only on the sex industry.

The research often conflates human trafficking with sex trafficking

For example, one widely cited study, from the London School of Economics and Political Science (LSE), suggested that the decriminalization of sex work in several countries led to increased human trafficking. Anti-decriminalization advocates often cite this study as evidence of decriminalization's downsides — it was, for example, the main study cited in a letter signed by celebrities and activists around the world asking Amnesty International, a human rights group, to not support decriminalization because it would lead to an increase in sex trafficking.

But the study reported an increase in all human trafficking, which includes forms of labor far beyond sex. It's entirely possible that the higher rates of human trafficking were in industries that had nothing to do with sex — the researchers, by their own admission, had no way to find out if that was the case.

In fact, it's entirely possible most of the reported increase in human trafficking had nothing to do with sex trafficking — since the illegal sex trade appears to make a small fraction of human trafficking. In 2010, the US State Department concluded, "Recent studies show the majority of human trafficking in the world takes the form of forced labor. The [International Labor Organization] estimates that for every trafficking victim subjected to forced prostitution, nine people are forced to work."

Ron Weitzer, a sociologist at George Washington University who studies human and sex trafficking, is generally skeptical of human trafficking statistics, since they're dealing with a practice that's underground. But he said "there's a logic" in the State Department's conclusion: "Think of all the different kinds of labor that one could be trafficked into — there's domestic work, agricultural work, factory work, mining, shipping. … The total has got to be much larger than the commercial sex sector. It makes sense that there might be nine times as much labor trafficking as sex trafficking."

"The claim that human trafficking victimizes a massive number of people is unsubstantiated"

Weitzer has been a vocal critic of studies that make sweeping conclusions about human trafficking. In 2014, he analyzed the data and research on trafficking in a paper, and found that studies' findings are commonly thinly sourced, rarely scientifically scrutinized, and often dramatized. He concluded, "The claim that human trafficking victimizes a massive number of people is unsubstantiated; it simply cannot be substantiated at the macrointernational level. The glaring evidentiary problems are so severe that even rough estimates of the worldwide magnitude of this hidden enterprise are destined to be fatally flawed. The same argument applies to national-level estimates."

It's not surprising that the data is bad, considering it's trying to analyze a practice that is by its very definition underground. But that exposes another flaw in the research: Any finding that decriminalization increases trafficking may only show that trafficking is easier to track when the sex industry is pushed into the open by decriminalization.

Take, for instance, the idea that there's more prostitution once it's legal. "Once you decriminalize, you make an invisible crime visible," Kastoryano of the University of Mannheim said. "You can suddenly count the number of prostitutes a lot more easily. So you have this huge bias that comes out that suggests there's more prostitution — but that's because they're not doing it undercover, they're not hiding it from you."

"Once you decriminalize, you make an invisible crime visible"

The LSE study acknowledges some of these issues, noting that the UN data it uses is bad before using it anyway. In their introduction, researchers state that the data "does not reflect actual trafficking flows" and that it's "difficult, perhaps impossible, to find hard evidence establishing" a relationship between legal prostitution and human trafficking — disclaimers that suggest the study's findings are essentially meaningless. And, again, this is one of the most respected, widely cited studies — the other research tends to be even worse.

When I asked Eric Neumayer, one of the LSE study's co-authors, about the limitations of the research, he acknowledged the data couldn't be broken down to distinguish between human trafficking and sex trafficking, and that the data was incomplete. "The data doesn't allow making such a distinction," he wrote in an email. "In fact, it doesn't even record the number of trafficked individuals."

The researchers argued they're using "the most reliable existing data." But the data is still pretty poor. Yet the researchers use it to make sweeping conclusions like, "Countries where prostitution is legal experience a larger reported incidence of human trafficking inflows."

Other data and research suggests decriminalization doesn't lead to an increase in trafficking

It's not just that the research linking decriminalization to an increase in human trafficking is incredibly flawed, but more reliable data suggests decriminalization doesn't lead to more trafficking.

After Germany loosened its anti-prostitution laws in 2002, prosecutions and convictions for sex trafficking — which remained illegal — began to steadily drop, according to a 2012 report from the Professional Association of Erotic and Sexual Services in Germany.

It's possible that the reduced number of prosecutions and convictions show laxer law enforcement against sex trafficking. But Weitzer said that's doubtful, since every country is very serious about going after human trafficking in general. Instead, the drop in prosecutions could indicate that there really wasn't an increase in trafficking after legalization. "What you'd expect is that if trafficking was increasing in Germany since 2002, then the authorities should have been prosecuting and convicting more over time," Weitzer said. "You see the opposite."

This also matches theoretical empirical work that suggests decriminalizing prostitution can reduce sex trafficking: If prostitution is legal and more accessible, the legal avenue will fill demand that would otherwise go to trafficked sex workers.

In a 2013 study, researchers at New York University and Stanford University developed an economic model that found criminalization results in more trafficking than decriminalization as long as law enforcement takes sex trafficking equally seriously under both policy regimes.

If criminalization is the only option, the study found governments should only criminalize the people who buy sex, not the sex workers who sell it. Not only can criminalizing sex workers inadvertently punish trafficked workers who sell sex involuntarily, but the study found it's also less effective for curtailing abuses and trafficking than criminalizing the buyers, whose demand for prostitution can be stymied through the threat of criminal penalties.

legal sex work can take up demand that would otherwise go to trafficked workers

But the study concluded that the best policy to limit trafficking is to decriminalize and regulate prostitution — much like other businesses are regulated — and maintain strict penalties for people who buy sex from unlicensed (and trafficked) workers. That way, legal sex work can take up demand that would otherwise go to trafficked workers, while police can continue using the full force of the law to crack down on illegal operations that may continue to use trafficked sex workers.

It's not certain that's the best way to decriminalize prostitution. Much like marijuana legalization, different places will try different approaches if decriminalization spreads. Over time, these various policy experiments should give us a clearer idea what the best approach will be.

But the weight of the evidence suggests that starting with decriminalization is a good idea. It's not the perfect policy, but it seems to be the best option.