He was Judge AD HOC of International Court of Justice in the case concerning sovereignty over Pedra Branca/Pulau Batu Pateh, Middle Rocks and South Ledge (Malaysia/Singapore) (2004–2008).
He is also an honorary visiting professor at Damodaram Sanjivayya National Law University, Visakhapatnam.
Dr. P.S Rao was educated at Andhra University, Waltair, India, and at Yale Law School (1967–1970).
Professor Rao worked as a Post Doctoral Fellow at the Woodrow Wilson International Center for Scholars, Washington, D.C., and at the Marine Policy Center of Woods Hole Oceanographic Institution, Woods Hole, Massachusetts.
He published Public Order of the Ocean Resources and has contributed several articles on the negotiation of the Law of the Sea Convention, 1982.