Peter has acted as counsel to States from all over the world, including Europe, Asia, Africa, Latin America, and the Middle East. His work for sovereign clients has also spanned all major areas of international law, including aviation law, criminal law, environmental law, health law, human rights law, humanitarian law, international organizations law, investment law, law of the sea, migration law, nuclear law, trade law, and United Nations law.

Peter has been invited to speak on issues of international law in more than twenty countries, including at the United Nations, multiple Ministries of Foreign Affairs, as well as at the flagship conferences of the American, European, Asian, and African Societies of International Law. He was recently named Co-Chair of the 2027 Annual Meeting of the American Society, one of the world’s largest annual gatherings of international law professionals. Peter has also widely published on international law, with his scholarship appearing in leading international law journals, books, and commentaries. Additionally, he was the author of the 2018 and 2021 Problems of the Jessup International Law Moot Court Competition.

Peter is a recipient of the prestigious Diploma of The Hague Academy of International Law and a graduate of Yale Law School, where he remains the only person in the history of the school to have twice received the Jerome Sayles Hess Prize for "excellence in the area of international law."