After the Citizenship (Amendment) Bill, 2019 was passed in both Houses of the Parliament, thousands of people descended on the streets in protest across the country.

DMK's youth wing secretary Udhayanidhi Stalin led a protest against the CAB as well at Chennai's Saidapet, where hundreds of party men joined him to tear copies of the Bill. Addressing the party's workers, Udhayanidhi claimed that the CAB is against Muslims and Sri Lankan Tamil refugees. The Bill was passed in both houses and became an Act following President Ram Nath Kovind's assent, but DMK MPs in the Lok Sabha and Rajya Sabha had voted against the Bill.

Udhayanidhi and 500 other party men, including Saidapet MLA Ma Subramanian, were then detained by the police before being taken to a private wedding hall. The DMK has, however, announced that another statewide protest will be held on December 17 against the AIADMK for backing the CAB in Rajya Sabha.

Under the new law, illegal migrants of the Hindu, Sikh, Jain, Buddhist, Parsi and Christian communities who have come from Pakistan, Bangladesh and Afghanistan until December 31, 2014, will be eligible for an Indian citizenship.