Sati--the practice of burning or burying a widow alive with her deceased husband--was commonplace in British India, especially in the "lower provinces" such as Orissa and Bengal. Lord Bentick observed in 1828 in a letter addressed to military officers, "Of the rite itself, of its horror and abomination not a word need be said. Every rational and civilized being must feel anxious for the termination of a practice so abhorrent from humanity...". The act was passed with other concerns. Indeed, the abolition of Sati manifested the Empire's desire to "civilize" (or culturally coloize) the oriental world. The ancient practice of sati was viewed as a blatant defiance of British ideology--a factor that could potentially threaten the security of British Territories in India. In 1829, the Government of Bengal passed the Sati Regulation Act in which sati was declared illegal and punishable by criminal courts.
However, this controversial practice was revived in independent India more than a century later. One of the most infamous cases was the burning alive of Roop Kanwar in Rajasthan on September 4th, 1987. The incident resulted in the passage of a Central Legislation known as the Commission of Sati (Prevention) Act, 1987.
Source: Pachauri, S. K. “Sati Problem—Past and Present”. Proceedings of the Indian History Congress, vol. 63, 2002, pp. 898-908. https://www.jstor.org/stable/44158159. Accessed 15 Feb. 2021.