[1] He was a former legal adviser to the Ministry of Foreign Affairs and Chairman of the United Nations Ad Hoc Committee on Comprehensive Convention on International Terrorism.
He is a current member of the International Law Commission[2] Perera has also served as a member of the Lessons Learnt and Reconciliation Commission and adviser to the All Party Representatives Committee.
He joined the Ministry of Foreign Affairs as an assistant legal adviser.
In a 32-year career Perera negotiated several bi-lateral and multilateral treaties in areas of foreign trade, investment, maritime boundary regimes, mutual legal assistance and extradition on behalf of the Government of Sri Lanka.
He has served as a visiting lecturer in International Law at the Faculty of Law, University of Colombo, Bandaranaike International Diplomatic Training Institute and at the General Sir John Kotelawala Defence University.