Philippa Webb > Twenty Essex > London, England > Lawyer Profile

Twenty Essex


Philippa’s practice covers all aspects of public international law. She acts for states 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, 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 in ground-breaking cases in international and English courts. Philippa advises on all aspects of immunity, including immunity from enforcement, diplomatic status, and related concepts such as act of state. She is appointed to the Attorney General’s Public International Law B Panel of Counsel.

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 QC during her presidency and  in this capacity was involved in 15 inter-state cases. Philippa has since  appeared as counsel and advocate  in 7 ICJ cases. Philippa has also worked as a legal adviser at the ICC.

She is Professor of Public International Law at King’s College London and Director of the Centre for International Governance and Dispute Resolution. She has held visiting positions at the University of Oxford, the Graduate Institute in Geneva, the University of Notre Dame and Université Paris Nanterre. She is on the Committee of Legal Experts for the Commission of Small Island States on Climate Change and International Law.

Philippa was shortlisted for 2022 “Barrister of the Year” by The Lawyer. She has been ranked as a top junior in Public International Law,  a ‘Future Leader’ in arbitration and a ‘UK Bar: Rising Star’.


French (proficient); Japanese (proficient)

Lawyer Rankings

London Bar > Public international law

(Leading Juniors)Ranked: Tier 2

Philippa WebbTwenty Essex ‘Philippa is an intellectual force to be reckoned with. She has masses of wealth of knowledge of public international law just simply stored in her head. Even though her academic credentials are impeccable, she is still practical and makes her advice and drafting accessible.’

Offering ‘perfect service‘ and ‘great breadth and depthTwenty Essex is an ‘outstanding chambers‘ that is ‘first choice for sensitive government matters and public international law‘. The set has an extremely broad selection of silks and juniors from a wide range of backgrounds, including former Legal Advisers to the Foreign and Commonwealth Office such as Sir Michael Wood KCMG and Sir Daniel Bethlehem KC. Sudhanshu Swaroop KC and Penelope Nevill are currently representing the Foreign Commonwealth and Development Office in Duarte Agostinho v Portugal & Ors, a claim before the ECHR brought by six Portuguese children against the Portuguese government and 32 other states including the UK over their failure to meet climate change commitments. Philippa Webb  is also representing a Filipino former domestic worker in the Saudi Arabian embassy in London in Wong v Basfar, a dispute before the Supreme Court concerning diplomatic immunity to cases of human trafficking and modern slavery.