This week, Iran's parliament approved a new amendment to a controversial law in the civil code that allows men to have as many sexual partners as they want – all sanctioned by sharia law under the term "temporary marriage".

Sex outside marriage is a crime in Iran punishable by 100 lashes or, in the case of adultery, potentially a sentence of death by stoning. However, a man and a woman can marry for a fixed period of time after performing specific religious rituals, in a practice called sigheh. The marriage can last for a few minutes up to several years without need to be officially registered. The man can end the sigheh almost at any time, but there is no divorce right for women in temporary marriages.

The new amendment, passed on Monday by 104 MPs who were all male, requires registration in certain circumstances such as those leading to a pregnancy but still largely allows sigheh without formal registration.

An opposing MP, Sattar Hedayatkhah, was quoted in the reformist newspaper Etemaad as saying: "From tomorrow, no woman can be sure that her husband is not in a sexual relationship with another woman. Therefore, there is now no difference between here [Iran] and the west. Anyone can have a sexual relationship with someone without the need to prove that there has been a 'temporary marriage' agreement."

Those who say sigheh does not need to be registered argue that it is a matter of privacy. Sex is indeed a private matter but the truth is that Iran does not respect people's privacy when it comes to sex. Sexual affairs outside marriage or temporary marriage are considered crimes. The sigheh law has long formalised temporary marriage in favour of men, giving them right to have sex with women for as long as they wish with law on their side.

The new amendments do little to recognise women's rights and let the old law continue to get away with discrimination against women, threatening the foundations of family in Iran.