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 particular expertise in state immunity. Philippa advises governments, organisations, corporations and individuals on all aspects of immunity, including immunity from enforcement, diplomatic status, and related concepts such as act of state and non-justiciability.

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 DBE QC during her presidency. Philippa has also worked as a legal adviser at the ICC.

She is Reader (Associate Professor) at King’s College London. Philippa is also on the editorial boards of the British Yearbook of International Law, Journal of International Criminal Justice, and Leiden Journal of International Law.

Philippa was ranked as a ‘Future Leader’ in the 2018 arbitration list and as a 2018 ‘UK Bar: Rising Star’ by Who’s Who Legal.


Year of call: 2006 (New York); 2016 (England and Wales)


French (proficient); Japanese (proficient)


  • American Law Institute’s project, Restatement Fourth, Foreign Relations Law of the United States: International Advisory Panel (2014–)
  • American Society of International Law
  • Attorney General’s Specialist Public International Law C Panel of Junior Counsel (2017–2022)
  • British Institute for International and Comparative Law: Public International Law Advisory Panel (2015–)
  • Clooney Foundation for Justice: Board Member and Secretary (2016–)
  • European Society of International Law: Board Member (2016–2020)
  • Human Dignity Trust: member of the Bar Panel (2018–)
  • International Law Association (British Branch)
  • The Honourable Society of the Inner Temple
  • Young Public International Law Group: Board Member (2016–)


  • Yale Law School: Doctorate (JSD) in Public International Law (2011)
  • Yale Law School: Masters (LLM) in International Law (2004)
  • European University Institute: Diploma in International Criminal Law, Cum Laude (2004)
  • University of New South Wales: Bachelor of Laws (LLB), University Medal, ranked first in year (2002)
  • University of New South Wales: Bachelor of Asian Studies (Advanced Japanese Studies) (Hons), University Medal, ranked first in year (2000)

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.