A Porirua man is facing two rare charges of failing to use a condom during sex with a prostitute.

The safe-sex law is thought to have been applied only about seven times since the Prostitution Reform Act was passed in 2003, and is punishable by a maximum fine of $2000.

The prostitute laid a complaint with Wellington police about the incident in October 2014.

The two charges against the man were heard by a justice of the peace in Wellington District Court yesterday. The man, 27, did not appear and was remanded on bail until another hearing scheduled for next month.

Before prostitution was decriminalised, sex workers were not able to complain about clients not wanting to use condoms, Prostitutes Collective national co-ordinator Catherine Healy said.

The culture was changing, but it could still be a struggle for prostitutes to insist on safe sex.

"Every sex worker will have a story related to a request for unsafe sex."

She said the latest charges were "certainly indicative of a different relationship where a sex worker feels that they have rights and can access justice and so forth if they feel a crime has been committed against them".

A Christchurch man who deliberately took off his condom during sex was the first to be charged under the law, in 2005.

He said he knew the prostitute would not have consented to his taking the condom off, so he did it without her knowledge.

She sought an HIV test, saying she was concerned the man had put her life at risk.

He was fined $400, along with $130 court costs.

Wellington CIB head Detective Senior Sergeant John van den Heuvel said the charges were unusual, and he had not seen the Prostitution Reform Act used before.

"Although it's not common to hear of a man being charged with this particular offence in New Zealand, police will consider seriously complaints made to us."

He said the nature of their profession meant sex workers were at risk of coercive behaviour from clients who did not want to use protection, but they had a right under law to expect their clients to comply with safe sex-obligations.

Police would consider charges against those who did not.