Professor Philippa Webb KC
Philippa’s practice covers all aspects of public international law. She acts for state and private entities in domestic and international courts on a wide range of issues. These include state and diplomatic immunities, territorial and maritime boundaries, treaty obligations, law of the sea, climate change, state responsibility, human rights, humanitarian law, law of international organisations and international criminal law.
She has been described as “the foremost expert on state immunity” and is counsel, often unled, in precedent-setting cases in international and English courts. In 2025 alone, she conducted advocacy before the UK Supreme Court in two cases on State immunity. Philippa advises on all aspects of immunity, including immunity from enforcement, diplomatic status, and related concepts such as act of state.In 2025, she was elected to the Institut de droit international, whose membership comprises the world’s 132 leading international lawyers.
Philippa is a specialist in relation to the International Court of Justice (ICJ). She served as the Legal Officer and Special Assistant to Judge Rosalyn Higgins GBE KC during her presidency and in this capacity was involved in 15 inter-state cases. Philippa has since appeared as counsel and advocate in a further 12 ICJ cases. She is currently instructed on cases representing half the ICJ’s docket. She also appears before the International Tribunal for the Law of the Sea and the European Court of Human Rights.
As a third strand to her practice, Philippa is counsel in inter-State arbitrations involving critical foreign relations issue, such as national defence, energy and water security.
She is full Professor of Public International Law at the University of Oxford and a Fellow of Exeter College. She is Co-founder and Director of the Oxford Institute of Technology and Justice.
Philippa was awarded “International Law Junior 2025” by Legal500. She was shortlisted for 2022 “Barrister of the Year” by The Lawyer. She is ranked as a top junior and ‘ Star Individual’ in Public International Law in the directories.