Since coming to The Catholic University of America in 1993, Professor Perez has taught a wide range of courses including public international law, international economic regulation, international regulation of telecommunications, national security and foreign relations law, a special seminar in homeland security issues, antitrust, contracts, torts, constitutional law, and conflict of laws.

He has been recognized with several teaching awards  Professor of the Year, 2021-22, and 2022-23, (Best First-Year Professor Award, Day Division, 2002, 2003, 2006, 2010, 2011, 2013 and 2016, and Best Evening Division Professor Award, 2004 and 2014) and was chosen by the graduating class as their Faculty Marshall in 2017 and 2023.  He has also published widely in international law topics, including United Nations peacekeeping and use of force, nuclear non-proliferation international trade, the recognition and enforcement of international judgments, and international human rights and international consumer protection.

Professor Perez's experience before coming to CUA included several years at the Office of the Legal Adviser of the U.S. Department of State, where his areas of responsibility included international civil and criminal mutual legal assistance, economic sanctions, peaceful nuclear cooperation and nuclear non-proliferation issues. Prior to that, he was as a corporate lawyer in the Antitrust Group of Shearman Sterling in New York.

He is a former editor of the Columbia Law Review and has served as a faculty adviser to CUA Law Review, as well as an advisor to the Jessup Moot Court Team, the National Security Moot Court Team and the VIS International Commercial Arbitration Moot Court Team.

In 2006, Professor Perez accepted life membership on the Council on Foreign Relations. The independent, nonpartisan think-tank and research organization has become a widely-known and deeply influential voice in U.S. foreign policy since its founding in 1921. He has also served as a member of the Inter-American Juridical Committee of the Organization of American States, to which he was elected by the OAS General Assembly held in Quito, Ecuador in June 2004, after being nominated by the Bush Administration for a 4-year term ending in 2008. In that capacity he reported on the OAS Juridical Committee’s work to the International Law Commission of the United Nations, meeting  in Geneva, Switzerland.

Professor Perez has served on the Editorial Advisory Committee of International Legal Materials, a publication of the American Society of International Law (ASIL), as chairman of the ASIL's International Security Interest Group, and a member of the amicus Committee of the Hispanic National Bar Association. 

As a member of the State Department’s Advisory Committee on Private International Law, he has served on several study groups concerning conflict of laws and international dispute resolution supporting the work of the U.S. State Department at the Hague Conference on Private International Law. Professor Perez has previously served as a member of the roster of arbitrators for the antidumping and countervailing duty disputes under chapter 19 of the North American Free Trade Agreement. He was also was selected by the Hispanic Bar Association of the District of Columbia as one of its "Rising Legal Stars" for 2006.

Professor Perez often serves as a commentator on issues of international and constitutional law, drawing not only on his scholarship but also his practice experience at the U.S. State Department and the OAS in the areas of national security, international trade and business, and private international law. He has appeared on "CNN International," Voice of America TV, EWTN, and a number of other domestic and foreign radio and TV news analysis shows.