Just as it is illegal to pay for sex
Again misinforming people, here read carefully and consider revising your statement.
First of all, prostitution is not forbidden in Poland but that dose not mean it's legal either since the laws that govern the legal work status do not apply to this profession. Furthermore the law governing suppression of the traffic in persons and of the exploitation, effectively forbids registering of prostitutes, running the houses of ill repute, or conducting any activity that would force anyone to prostitute themselves. The illegal act that is on the books and not associated with the above deals with the acquisition of money for such activity mainly as a third party a Pimp not a John.
Art. 204:
1. Kto, w celu osiągnięcia korzyści majątkowej, nakłania inną osobę do uprawiania prostytucji lub jej to ułatwia, podlega karze pozbawienia wolności do lat 3.
2. Karze określonej w 1 podlega, kto czerpie korzyści majątkowe z uprawiania prostytucji przez inną osobę.
Poland chose an abolition approach to deal with prostitution. Not to punish the poor souls that choose to engage in such activity out of their own accord whatever the reason might be but rather to inflict the penalty on a third party that would profit from such activity. So while a single working girl somewhere on the street corner (Tirówa) and her John are not engaging in an illegal activity anyone running or visiting a brothel is.
