The International, Impartial and Independent Mechanism - Syria (IIIM) was established in December 2016 by the General Assembly to assist in the investigation and prosecution of persons responsible for the most serious crimes under International Law committed in the Syrian Arab Republic since March 2011.

The IIIM is a justice facilitator working towards accountability for core international crimes, particularly war crimes, crimes against humanity and genocide, committed in the Syrian Arab Republic from March 2011 onwards. It collects, preserves and analyses information and evidence. It then shares, either on request or proactively with competent jurisdictions, material and analytical products relevant to on-going investigations. The IIIM does not have prosecutorial powers. Rather, it assists those jurisdictions which are leading investigations and prosecutions against suspected perpetrators of crimes in Syria.