The term Freier colloquially refers to the client of a sex worker. The etymology traces back to the Middle High German "vrîen" (to solicit, to court). In professional discourse, the terms "Kunden" or "Klienten" are increasingly used.
In Switzerland, the use of sexual services by adult, voluntary sex workers is not punishable. The client only becomes punishable if he engages the services of minors (Art. 196 StGB) or individuals in a recognizable state of coercion (victims of human trafficking, Art. 182 StGB) — even if he only accepts the coercive situation.
Politically, there has been ongoing discussion for years about whether Switzerland should adopt the Nordic Model (prohibition of purchasing sex), which criminalizes the purchase of sexual services outright. Sex worker associations (ProCoRe, Aspasie) oppose this — it would push the industry into illegality.