Three of the judges called the controversial practice "unIslamic, arbitrary and unconstitutional". One of the judges, Justice Kurien Joseph, said the practice was not an essential part of Islam and enjoyed no protection.
Chief Justice JS Khehar, in a differing opinion, said that personal law could not be touched by a constitutional court of law
Islamic scholars say the Koran clearly spells out how to issue a divorce - it has to be spread over three months, allowing a couple time for reflection and reconciliation.
Activists say most Islamic countries, including Pakistan and Bangladesh, have banned triple talaq, but the custom has been thriving in India.
In recent years, many cases have emerged of Muslim men in India divorcing their wives by issuing the so-called triple talaq by letter, telephone and, increasingly, by text message, WhatsApp and Skype. A number of these cases made their way to the courts as women contested the custom.
source: BBC News