The Philippine Supreme Court on Tuesday began hearing arguments in a petition to declare President Rodrigo Duterte’s deadly war on drugs unconstitutional. In a petition filed last month, lawyers from the Free Legal Assistance Group (FLAG) argued the anti-drug campaign is unconstitutional because it allows police to kill suspects in the guise of “neutralizing” them during raids and sting operations. Also on Tuesday, Philippine President Rodrigo Duterte rejected allegations by a rights group that troops engaged in looting during the bloody battle against Islamic State followers in the southern city of Marawi. More than 3,900 Filipinos have been killed in what the police called self-defence after armed drug suspects resisted arrest in the 16 month-long campaign.