In 2017, the Commission on Human Rights (CHR) reported that the war on drugs during the administration of then President Rodrigo R. Duterte was not only marked by extrajudicial killings but also by a systematic pattern of abuse, torture, and arbitrary executions. 

Reports from victims’ families, testimonies from former police officers, and the work of investigative journalists documented these alleged abuses. Amnesty International and Human Rights Watch conducted in-depth investigations, gathering evidence that pointed to the Philippine government’s involvement in these atrocities.

This led to the filing of complaints with the International Criminal Court (ICC), which investigates and prosecutes crimes of genocide, war crimes, and crimes against humanity.

The case against Duterte began to take shape in 2018, when the Philippines was still a member state of the ICC. Under the Rome Statute, the governing treaty of the ICC, the court has jurisdiction over crimes committed by nationals of its member states, and the Philippines was legally bound to cooperate with investigations at the time.

The charges filed against Duterte stemmed from accusations that his administration’s actions, as part of the war on drugs, amounted to crimes against humanity. These crimes, according to the Rome Statute, include acts such as murder, extermination, enslavement, and other inhumane acts that are committed as part of a widespread or systematic attack on civilians. 

The ICC’s Office of the Prosecutor opened a preliminary examination into the Philippines’ drug war in 2018, focusing on the widespread pattern of extrajudicial killings and other atrocities.

The parties that played a significant role in the filing of these cases included a combination of human rights organizations, victims’ families, and individual citizens. Human rights groups, such as Human Rights Watch and Amnesty International, were at the forefront of documenting the crimes and submitting their findings to the ICC. These organizations gathered testimonies from victims' families, former law enforcement officers, and independent witnesses, all of whom corroborated the allegations of extrajudicial killings and other human rights violations.

One of the most prominent advocates for holding Duterte accountable was Filipino lawyer Jude Sabio, who filed a complaint with the ICC in 2017. Sabio, who had previously represented a former police officer and whistleblower, claimed that Duterte’s administration was directly involved in a policy of widespread extrajudicial killings. Sabio’s complaint included evidence from a former police officer named Edgar Matobato, who testified that Duterte had ordered the killing of criminals when he was mayor of Davao City, even before becoming president. Sabio argued that these actions were part of a broader pattern of crimes against humanity that had escalated under Duterte’s presidency.

Another key figure in the legal battle against Duterte was then Senator Antonio Trillanes IV, who had been a vocal opponent of Duterte’s policies. 

Trillanes, Sabio and other human rights defenders publicly called for an investigation into Duterte’s drug war and the crimes being committed by the government, as well as to amplify the voices of victims and human rights groups, bringing global attention to the situation.

In response to the mounting international pressure, Duterte and his government rejected the ICC’s jurisdiction and withdrew from the Rome Statute in 2019, effectively pulling out of the court. 

However, the ICC maintained that its jurisdiction remained intact for crimes committed while the Philippines was still a member. Despite Duterte’s withdrawal, the investigation into his actions continued, and in 2021, the ICC filed formal charges against Duterte for crimes against humanity. These charges focused on murder, torture, and other inhumane acts committed during the drug war.