Researchers from the LSE did a study of 150 countries and found that there’s more human trafficking where prostitution is legal/decriminalised. A study for the European Parliament came to the same conclusion, and so does economic theory.

This isn’t surprising when we consider that one of the key purposes of the criminal law is to make clear the boundaries of what is and isn’t acceptable. So, we have laws against theft and driving dangerously, and violence against people, and even animals, because these behaviours conflict with the interests of a modern democratic society.

When something that was previously a criminal offence is made legal, it sends out the message that society now considers the former offence to be acceptable. This invariably leads to more people engaging in that behaviour.

So, when a country decriminalises the sex trade, it is announcing that buying sexual access to other people and profiting from their prostitution are now considered acceptable. This inevitably leads to more men buying sex more frequently, and more pimps and brothel keepers wanting to get their hands on all that extra money.

But there aren’t enough women to fill this increased demand, because women who have genuine choices don’t generally choose to go into prostitution. This means that those who want to cash in on this extra money have to use coercion, force, trickery, or taking advantage of (mostly) young women’s vulnerabilities to recruit and retain women and girls in prostitution. This fits the United Nations definition of sex trafficking.

And if you have any doubt about the amount of money that can be made, consider the case of Phillip Stubbs, who was found guilty of two counts of brothel keeping at Bristol Crown Court in 2015. When the police raided his home they discovered more than 100 cars – including Mercedes, Bentleys, and Lamborghinis – in a temperature controlled basement, as well as an indoor swimming pool. He had made a massive fortune from exploiting the prostitution of women in brothels in the Bristol area.