In May 2018, long-running protests against the expansion of Sterlite Copper's smelting plant in Thoothukudi, Tamil Nadu, culminated in police opening fire on demonstrators. On 22 May, the 100th day of the anti-Sterlite protests, thousands marched toward the Thoothukudi Collectorate in defiance of prohibitory orders. Protesters overpowered police lines, pelted stones, and torched vehicles; police responded with lathi charges, tear gas, and eventually live gunfire. Police killed 12 people on 22 May and one more on 23 May; a man who had been in a coma after being injured in a lathi charge died in October 2018, raising the death toll to 14. Officers were reported to have fired without formal warning, including from atop a van, with witnesses and video suggesting deliberate targeting of protesters' heads.
Autopsies found that 12 of the 13 people killed during the protests were shot in the head or chest, and about half were shot from behind, despite police rules requiring shots to be aimed below the waist. In a related incident on 25 May, a woman was killed when a bus was torched during unrest in Srivaikuntam.
The protests were rooted in decades of environmental grievances against the Sterlite plant, operated by Vedanta Limited, including pollution studies dating to the 1990s and 2000s that found elevated respiratory illness, contaminated groundwater, and hazardous soil arsenic levels near the facility, as well as gas leaks in 1997 and 2013. The immediate trigger for the 2018 unrest was Sterlite's plan to double smelting capacity.
In the aftermath, the Tamil Nadu government sealed the plant in May 2018, and authorities imposed a five-day internet shutdown across Thoothukudi, Tirunelveli, and Kanyakumari districts. The Central Bureau of Investigation (CBI) registered cases in November 2018 against unidentified police personnel and revenue department officials for the deaths of 14 protesters, alleging criminal intimidation and criminal conspiracy. In December 2023, a Madurai court rejected the CBI's chargesheet, criticizing it for naming only one police officer and ordering further investigation; in July 2024 the Madras High Court found the CBI had shown "serious lapses" and appeared to have lost its independence.
The Justice Aruna Jagadeesan Commission of Inquiry, which submitted its report in August 2022, described the firing as "unprovoked," stated police had fired on "fleeing protesters," and singled out the then District Collector for "abdication of responsibility, gross negligence and ill-conceived decisions." The report also found that then Chief Minister Edappadi K. Palaniswami was being updated on developments during the firing, despite his public statement that he had learned of it only through media reports. United Nations human rights experts condemned the police's use of force as "excessive and disproportionate." Environmental activist S. Mugilan, who alleged a police-company conspiracy behind the shooting, disappeared in February 2019 and was found five months later, claiming he had been abducted; the Madras High Court later dismissed his account as fabricated.