Public international law

Our established team has advised on some of the highest profile and most complex arbitration matters globally and is highly regarded in the field.

We advise on the entire spectrum of international law work, ranging from State-State disputes before the International Court of Justice (ICJ) and ad hoc arbitral tribunals to advising on human rights disputes (including before U.N. committees) and international law in national courts.

Whether you’re looking for advice on international investment law, land and maritime boundary disputes, the law of the sea, sovereign and diplomatic immunity, sanctions, trade law, international environmental law, human rights litigation, international humanitarian law, the law of international organisations or enforcement – we can help.

Experience advising both investors and States

We have an established investor-state arbitration practice with numerous investment treaty arbitration cases, representing both international investors and sovereign states.

Our dedicated team works with clients around the world to resolve investor-State disputes under all the major arbitration rules, as well as ad hoc arbitrations across a wide range of sectors including, but not limited to, energy, natural resources, infrastructure, manufacturing, technology, construction and finance.

We also have an experienced practice advising Governments on drafting investment treaties and investment legislation, a rare focus in private practice in the field of public international law.

International support to suit your needs

Made up of more than 20 lawyers worldwide, our team is spread across London, New York, Milan, Singapore, Hong Kong and the British Virgin Islands. Our members are fluent in numerous languages, including French, Spanish, Italian, Russian, Arabic, Chinese and Turkish and are qualified in both common and civil law jurisdictions, with extensive experience working in international organisations and emerging markets. We act as strategic advisors, conducting our own oral advocacy in public international law and human rights matters. These key factors contribute to the strength of our practice.

We are able to advise a variety of clients, namely Governments, multinational corporations, international organisations, non-governmental organisations and individuals, in the context of sensitive disputes involving different regions of the world, including in the Middle East, Africa, Asia, CIS countries, Europe, Russia and Latin America.

A leading practice

Clients have praised our team’s ‘deep technical knowledge’ and ‘impressive ability to assess and navigate complex legal and factual situations’, whilst also acknowledging our ‘responsiveness and professionalism’ as being ‘of a very high order’ and appreciating our ‘excellent customer focus’.

Members of the team have also been commended for blending ‘strategic thinking with excellent client management skills’ and are known for their ‘practical and creative strategies’.

For further help or information

Get in touch

17 September 2021 - Article

Sovereign Wealth Funds: a detailed analysis of transnational regulation and dispute resolution

Read More

29 September 2020 - Firm News

Withers appoints former Attorney General Rt Hon Geoffrey Cox QC MP as Consultant Global Counsel

Read More


2022 Chambers UK: leading firm for public international law

2022 Legal 500 UK, leading firm for public international law

Leading firm for public international law

Leading firm for public international law

Managing political risk

We are in uncertain political times. Whether economic, personal or otherwise, we can help individuals and businesses take practical steps to reduce their exposure.

Read more

Track record

  • Advising a State in a potential State-to-State dispute in relation to international environmental law issues.
  • Advising a State in relation to discrimination issues arising under a human right treaty.
  • Advising a State in relation to issues pertaining to freedom of navigation and the law of the sea.
  • Advising a government in the Middle East on its investment treaty program.
  • Advising an NGO in relation to human rights issues to present a shadow letter to the UN Committee on the Rights of the Child.
  • Advising an international organisation in relation to EU-Russia sanctions.
  • Advising a German investor in an ICSID investment treaty arbitration claim in relation to discrimination measures taken by an African State.
  • Advising an Italian client in a dispute over an investment in the energy sector and ICSID investment treaty arbitration claim against a European state. Our client is seeking damages for breach of fair and equitable treatment, expropriation and other treaty standards.
  • Conducting an extensive project for a Government client advising them on international investment law issues and drafting an innovative model bilateral investment treaty.
  • Advising a Caribbean Government on a range of international investment law issues.
  • Representing a Mauritian energy company as counsel and advocates in an investment treaty arbitration against Pakistan under the UNCITRAL arbitration rules.

Hussein Haeri combines deep technical knowledge of investment treaty arbitration with clarity of strategic direction and impressive project management skills. He demonstrates excellent customer focus and sound judgement.

Thomas Le Feuvre, Head of International Agreements, Government of Jersey

Withers LLP is ‘a good firm for PIL work’; it has a particular focus on investor-state arbitration, but the practice also advises on enforcement and sovereign immunity issues, as well as human rights. Other notable areas include advising governments on the enforcement of international trusts and tax treaties; and the team has notable Middle East and energy sector expertise. Hussein Haeri is ‘very strong’; he led the representation of a UK investor in an International Centre for Settlement of Investment Disputes arbitration against the Czech Republic.

Legal 500, 2017

Hussein Haeri impresses market commentators with his ‘combination of strong litigation skills with expert knowledge in public international law.

Who's Who Legal, 2017

Withers LLP is very strong in this field with a real diversity of work across all types of public international clients. The practice is particularly well-known for its investor-state arbitration practice as well as state-state disputes; notable geographical strengths include the Middle East and Africa and the team regularly works on infrastructure and energy-related matters. It is also noted for human rights and trade law issues. Highlights included representing A11Y, which specialises in assistive technology solutions for blind people, in an ICSID-administered investor-state arbitration against the Czech Republic under the UK-Czech Republic bilateral investment treaty. Public international law head Hussein Haeri combines huge intellectual powers with great client handling and gives straight-to-the-point advice.

Legal 500, 2019

Meet the team

We can also help with

Would you like to hear more from us?

Visit our subscriptions page to tell us a bit more about what you’re interested in so we can send you relevant news.