Atty. Mel Sta. Maria had extensive litigation practice. He was one of the lawyers in a number of national impact cases filed with the Supreme Court and handled by the Ateneo Human Rights Center (AHRC). These cases include the East Timor injunction case, the Davide Impeachment controversy the people's initiative and the Neri-Executive privilege case. He is one of the petitioners in the case filed before the supreme court questioning the constitutionality of some of the provisions of the Cybercrime Prevention Act. He has also been engaged as an expert witness in the field of Philippine Contract Law in international arbitrations.