Sex trafficking is the practice of trafficking people (normally women) in order for them to enter into sex work. Often, this is done by force, with women having to participate in prostitution under threat of violence or to ‘repay debt’. Roughly 4.8 million people today are thought to be trapped in situations of sexual exploitation due to sex trafficking. 
Prostitution and human trafficking have a direct and severe link. Legalised prostitution has been linked to higher rates of human trafficking, as legalising prostitution leads to an increase in demand and therefore increased incentive for traffickers. The decriminalisation of prostitution also provides a cover under which perpetrators can traffic victims. The only way to counter this is for prostitution to be illegal, so that traffickers do not have this cover to hide behind. Some proponents of this argument believe there is no distinction between prostitution and sex trafficking. For instance, the Palermo Protocols released by the United Nations in 2000 does not require transportation or a lack of consent to be part of the definition of trafficking, insinuating that any woman in prostitution is a victim. Any distinction between trafficked and non-trafficked women in prostitution is irrelevant, as men who pay prostitutes do not care whether women are trafficked or not; they do not ask women if they are there voluntarily.
Decriminalising prostitution decreases incidents of sex trafficking. Access to a steady stream of legal and willing prostitutes eliminates the demand for trafficked prostitutes. Decriminalisation can also promote the human rights of sex workers, making trafficking easier to report and prosecute. It may be, therefore, that countries where prostitution is decriminalised have a higher likelihood of trafficking being reported rather than actually having higher rates of trafficking. Sex trafficking has been called the “new war on drugs”,  taken up as a cause by politicians due to its salaciousness. It is thinly veiled, anti-sex worker rhetoric. It is impossible to definitively prove the impact that prostitution has on trafficking as there are not reliable statistics on trafficking, and statistics are often exaggerated.
[P1] Demand for prostitution causes sex trafficking to increase. [P2] Decriminalisation of prostitution increases demand. [P3] Therefore, anything but the illegality of prostitution will increase sex trafficking rates.
[Rejecting P1] The causes for the rates of trafficking cannot be definitively proven.