A ruling by India's top court against husbands who have sex with their child brides will protect millions of girls and may propel efforts to make marital rape a crime in the conservative nation, according to campaigners.

The Supreme Court on Wednesday struck down a decades-old clause in the country's rape laws permitting a man to have sex with his wife if she is between ages 15 and 18 — ruling that it is rape, and therefore a criminal offense.

The age of consent in India is 18 years old, and petitioners challenging the exemption in the country's rape laws said it was in contradiction with other legislation.