The Philip C. Jessup International Law Moot Court Competition is the world's largest moot court competition, with participants from over 500 universities in more than 80 countries.

Moot courts are competitions in which law students prepare a case from the point of view of both parties involved. They must defend one of them in court. The case is chosen in advance and the students have a set time to prepare. In moot courts, the judges are usually law professors, lawyers or even practising judges.

The Philip C. Jessup International Law Moot Court Competition is a simulation of a fictional dispute between countries before the International Court of Justice, the judicial organ of the United Nations. Only one team is allowed to participate from each university. Teams prepare oral and written pleadings arguing both the applicant and respondent positions of the case.

Professor Collantes had previously participated in two other Spanish rounds of this competition. In the most recent edition, the other judges included Jesús María de Alfonso, the president of the Arbitration Court of Barcelona; Eugeni Gay, the former vice president and judge emeritus of the Spanish Constitutional Court; associates from the law firms Cuatrecasas and Uría Menéndez Lawyers; and Oriol Casanovas, the Head of International Public Law at Universitat Pompeu Fabra.