The Supreme Court of India has ruled that a Muslim man’s bigamous marriage to his wife’s sister "was merely irregular though not illegal".

This judgment would put a stop to the practice by certain persons who marry sisters of their wives and then refuse maintenance, citing the Muslim custom that termed the second marriage to the wife's sister as void.

That is exactly what happened in the case before the court.  A Muslim man married his wife’s sister with the consent of his first wife.  Later he began neglecting his second wife, who then sued for support.  Lower courts upheld the second wife's claim.

The appeal to the Supreme Court was initiated, not by the man, but by his first wife, who argued that her sister was not entitled to financial support because the second marriage was void.  The court, however, said it was legal and ordered the first wife to pay up.

And here I thought sisterhood was powerful.