Sale of the body is immoral
By selling their bodies, sex workers are losing part of themselves.
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. This is known as the "scale effect": as the prostitution industry grows, the trafficking industry proportionately grows with it. The decriminalisation of prostitution provides a cover under which perpetrators can traffic victims. Decriminalisation offers legitimacy to traffickers, as they can portray themselves as part of a legitimate sex industry. The argument for decriminalisation assumes a highly optimistic view of the ability that it has to curb trafficking. The Advocates for Human Rights state that decriminalisation "assumes a change in attitude and behavior by system actors and relies on system actors to determine when “voluntary” becomes exploitative while limiting access to investigate." By decriminalising prostitution, a vital safeguard is taken away as the law then has a much higher threshold for the amount of evidence they need to gather against traffickers. The only way to keep trafficking victims safe is for prostitution to be illegal, so that traffickers do not have this cover to hide behind. The neo-abolitionist view of prostitution dictates that 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. Both prostitution and sex trafficking are part of misogynistic systems that pray on vulnerable women, rewarding those who pray on them. This view of prostitution as equitable to sex trafficking has been adopted into official literature. 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 of a crime. Women in prostitution are all victims of an oppressive system that robs them of their agency, and the law should reflect this.
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. Studies only show that based on most available information, reported rates of trafficking are higher in instances where prostitution is decriminalised. However, 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. Decriminalisation empowers trafficked women to seek help if they are being exploited, without fear of themselves then being prosecuted. Decriminalising prostitution could equally decrease incidents of sex trafficking, as access to legal and willing prostitutes eliminates the demand for trafficked prostitutes. A decriminalised market has been found to be likely to decrease trafficking where prostitution is a viable option for voluntary (as opposed to trafficked) sex workers. Sex trafficking has been called the “new war on drugs”,  taken up as a cause by politicians due to its salaciousness. Trafficking is conflated with being a sex worker who is also a migrant. It is thinly veiled, anti-sex worker rhetoric. By portraying all migrant sex workers or indeed all sex workers as victims of trafficking, they are dehumanised and painted only as victims without personal agency. The vast majority of migrant sex workers do not feel their work is exploitative or that they are doing it against their will. In fact, a study by Mai shows that the many even see it as a positive alternative to the exploitative environments they encounter at other, low-paying jobs.
[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.