The legal policy to prostitution was always a complex issue, in many countries laws were changing from criminalization, to partly-, or fully decriminalization, tolerance, spatial segregation or even regulation during the centuries and were often reversed after seeing different problems arising from newly adopted policies.
Punishing the client and pimp, while not punishing the prostitute is however a relatively new approach, that provides benefits for fighting criminals and protecting victims of abuse/coerced prostitutes.
As every law, prostitution law has advantages and disadvantages and conflicting interests cannot necessarily be resolved in an equal manner, that is we have to prioritize which values needs the most support when adopting a prostitution policy. Should it support the willing prostitutes, whose wellfare is not depending on the money they receive, the non-criminal third parties, like providers of travelling and location for the business, should it support local residents who complain about the side-effects of prostitution, public health policies against the spread of STIs, the johns (who buy sex), or the abused victims coerced to become prostitutes?
The position of this argument is that the first priority should be the support of abused/coerced prostitutes, and lowering their absolute numbers when deciding over a prostitution law. All other support for other interests are secondary of importance.
Following this logic, how can we best serve the interests of coerced victims and lower their numbers effectively? 1) Prevent their entry and 2) support their exit from prostitution.
1) Punishing the demand, can decrease the total number of prostitutes required in the sector and thus decrease the absolute number of those prostitutes who are coerced as well. This hurts the interest of high-end prostitutes, pimps and johns but serves the interest of coerced victims. If we follow the priority, we value this action as beneficial. Direct policy: punish clients.
2) Providing alternatives for prostitutes to exit this business also help coerced victims to find a way out. This hurt the interests of pimps and johns.
Direct policy: cease persecution of prostitutes, to not fear reprisal when reporting their history to authorities, rehabilitation centres, employment options, helping organizations, translations, education etc.