Leiden previously won the award in 2010. Representing this year's team were Ana-Maria Enache and Sarah Cunningham, from Leiden's LL.M. program in Public International Law (Reg.), and Olivia Nederlandt, Andrew Mura, and Jodie Gummow from the LL.M. Advanced program. The team was coached by Christian De Vos and Jennifer Easterday from the Grotius Centre for International Legal Studies.

After winning the Dutch national rounds in February against the University of Amsterdam and Utrecht University, the team performed exceeding well in the preliminary international rounds of the competition. The team earned high marks for its three memorials and oral arguments. Leiden was also amongst the top six schools to advance to the semi-finals round that took place on Thursday, April 26. Ana-Maria Enache argued on behalf of the team as defense counsel before a bench that included Judge Morrison of the International Criminal Court, Judge Nosworthy of the Special Tribunal for Lebanon, and Judge Nyambe of the International Criminal Tribunal for the former Yugoslavia.

The 2012 case involved a variety of complex and timely legal issues, including the gravity threshold for crimes against humanity, modes of liability, head-of-state immunity, and the application of the complementarity principle. The finals, which took place at the ICC on Friday, April 27, were won by the City University of Hong Kong.