To enforce that law, Singapore maintains two separate Marriage Registries. Registry of Muslim Marriages (ROMM) for Muslims and Registry of Marriage (ROM) for non-Muslims. Polygamy is legally prohibited.

On the other hand, Buddhists can freely marry Hindus or Christians or any other religionists or even Atheists. But the cross marriage of a Muslim man to a non-Muslim bride is not allowed unless the woman is a willing convert to Islam.

Singapore Government strictly enforces Muslim Law Act (1968) and ROMM is one significant part of that act in keeping the Muslim population at roughly 15% of total 5.4 million Singaporeans.