At the Rwanda Tribunal, Petit drafted indictments in the Government,[clarification needed] Butare, Hategekimana, and Nizeyimana cases.
In UNMIT, he exercised criminal investigative functions and led the prosecutions of persons suspected of mass crimes committed during a period of national political transition in East Timor.
[1] Petit was called to the Quebec Bar in 1987 and has spoken and written extensively on international humanitarian and human rights laws.
In 2009, he received the Frederick K. Cox International Humanitarian Award for Global reform at the Case Western School of Law, Cleveland.
Petit was selected in 2011 as one of the four final candidates to succeed Luis Moreno-Ocampo as the Prosecutor of the International Criminal Court in the Hague.