In addition to bilateral and multilateral investment treaty-related disputes, Allen & Overy LLP's London public international law (PIL) team advises on international treaties and conventions, international sanctions regimes, sovereign immunity and state succession issues, along with boundary claims, international humanitarian law, and trade and WTO issues. London PIL practice head Mark Levy KC acts in major investment treaty arbitration cases; Andrew Denny is head of the business and human rights group; James Freeman acts in heavyweight investment treaty claims; and Matthew Townsend specialises in trade-related matters. At counsel level, Naomi Briercliffe's experience includes claims against states; and Sarah Garvey is 'one of the best lawyers around'. In 2022 the firm hired investment treaty and PIL specialist David Herlihy from Skadden, Arps, Slate, Meagher & Flom (UK) LLP, with Kate Davies KC going in the opposite direction; and promoted investment treaty disputes specialist Guled Yusuf to partner. Suzanne Spears left in 2022 to set up a specialist business and human rights boutique.

Clifford Chance LLP‘s recent track record includes ongoing treaty negotiations for the UK; international human rights cases; representing governments and companies in investment treaty claims; and advising on government policy compliance with trade and investment treaties. The practice is jointly led by Rae Lindsay, whose practice covers business and human rights, and the status, immunities and privileges of international organisations; highly rated investment treaty protection specialist Audley Sheppard KC; and Jessica Gladstone, who focuses on PIL and international disputes, climate change, international trade, sanctions, and business and human rights. The second line of advisers features UK and European sanctions head Michael Lyons; and at senior associate level, Anna Kirkpatrick frequently leads on PIL work, Carla Lewis focuses on EU and UK restrictive measures, Christina Schuetz is an investment treaty arbitration expert, Anne Collins is a PIL specialist, and Jeremy Stewart advises on WTO law and free trade agreements.

‘One of the leading PIL firms in the world‘, Debevoise & Plimpton LLP‘s London practice consistently acts for sovereign governments, corporations, international organisations, NGOs and high-profile individuals. Recent work ranges from BIT claims, humanitarian law and international human rights law, to international environmental law, Law Of The Sea, state immunity, and acts of state doctrine. Former UK Attorney General Lord Peter Goldsmith KC is global co-chair of the firm’s PIL group, his track record including appearing before several international courts and tribunals; Samantha Rowe focuses on PIL and international arbitration matters; and co-head of the firm’s Africa practice group, Patrick Taylor, advises on PIL issues, human rights and investment disputes. The second line of practitioners features experienced international counsels Aimee-Jane Lee and Conway Blake, along with senior associate Merryl Lawry-White, who ‘has excellent knowledge and experience in PIL matters‘; and Monika Hlavkova, whose ‘preparation is impeccable‘.

‘The strongest PIL boutique in London‘, Fietta LLP has ‘vast experience in PIL matters‘. Dedicated to PIL and international arbitration work, the practice is routinely instructed by sovereign clients in their most sensitive PIL matters globally; and in contentious work, the team represents both investors and respondent states in investment arbitration. With ‘remarkable knowledge of PIL‘, founding partner Stephen Fietta KC regularly acts for sovereign states in high-profile territorial disputes; and Jiries Saadeh, ‘an absolute star of his generation‘, represents state and investor clients in international investment treaty cases. At counsel level, Australian lawyer Ashique Rahman is a founding board member of the Young Public International Law Group, a network of PIL practitioners; and Laura Rees-Evans and Oonagh Sands also both assist with complex PIL issues.

‘Without doubt the leading firm in public international law‘, Volterra Fietta‘s large PIL practice acts for private entities, states and international organisations across the full range of PIL work, including International Court of Justice (ICJ) cases, maritime boundary claims, and investment treaty and International Centre for Settlement of Investment disputes (ICSID) arbitrations. The firm also fields specialists in state immunity cases, the laws of war and international humanitarian law, along with international human rights, state responsibility, and WTO and international trade law. The ‘best public international lawyer around‘, Robert Volterra assists with a wide range of PIL issues; Graham Coop is particularly focused on the energy, natural resources and infrastructure sectors; and the experience of recently elevated partner Peter Flint includes acting for governments and commercial parties in international disputes. Recently promoted counsel Gunjan Sharma, and associates Angela Ha and Jehad Mustafa, all have extensive PIL experience.

Arnold & Porter’s London international arbitration, global law and public policy groups are best known for their experience in representing states and corporate clients in investor-state arbitrations throughout the world. The principal figures are Patricio Grané Labat, whose track record includes high-profile and politically sensitive investment treaty cases; international arbitration specialist David Reed; Dmitri Evseev, whose broad practice includes advising states and organisations on PIL matters, including international humanitarian law and the relationship between investment protection treaties and EU law; and Monty Taylor, ‘one of the best three PIL solicitors of his generation‘. Notable growth for the group includes the recruitment of international investment law and PIL expert Álvaro Nistal (‘no doubt an excellent addition to the team‘) as counsel from Volterra Fietta in June 2021; and at senior associate level, Bart Wasiak, Tim Smyth and Alice Osman all act on PIL disputes.

Cooley (UK) LLP‘s broad PIL practice ranges from investment treaty and international trade disputes and advisory work, to Law of the Sea advice for coastal states, issues of state responsibility in highly contentious regional areas, and international asset recovery work. The London office also has notable investor-state arbitration strength. The practice is led by James Maton, whose PIL expertise spans investor-state arbitrations and treaty disputes; Laurence Harris‘ practice covers complex commercial, public law, and cross-border fraud and asset tracing disputes; and the ‘responsive, thorough and engaged‘ consultant John Brown is a Law of the Sea specialist. The second line of practitioners comprises Henry Stewart, whose PIL litigation expertise includes asset recovery and anti-corruption matters; and associate Juan Nascimbene, who focuses on international treaty arbitration, PIL work and international economic law. Former independent consultant Tim Daniel formally retired from the firm during 2022.

Freshfields Bruckhaus Deringer LLP‘s ‘diverse team of serious thinkers‘ is best known for handling high-profile, high-value and politically sensitive disputes. Recent work includes PIL work for states (including state-to-state disputes), and investment treaty arbitrations involving complex PIL issues; and the firm’s international law advisory practice advises states and other stakeholders on issues of state responsibility, treaty drafting, environmental law, use of armed force, territorial and maritime boundary disputes, sanctions and embargoes. ‘Exceptional practice head‘ Will Thomas KC is a highly-experienced PIL and investment arbitration practitioner; London arbitration head Sylvia Noury KC is a recently appointed silk, who specialises in PIL issues and investment treaty arbitration, with a focus on Africa, India and Latin America-related matters; and associate Joshua Kelly acts in disputes involving Russia, the CIS, Africa and offshore territories. WTO and free trade agreement expert Lorand Bartels MBE joined as counsel in April 2021 from Linklaters LLP.

With ‘real strength in depth in PIL and its intersection with arbitration‘, Herbert Smith Freehills LLP‘s recent track record includes urgent advice to clients on the PIL-related impact of the Russian military action in Ukraine, including international sanctions, the laws of war, international humanitarian law, investment protections, state immunity and international human rights. The team’s coverage also includes advice on international law issues arising from the COVID-19 pandemic, climate change and environment-related international law and regulation, and the UK’s exit from the EU. ‘Exceptional talent‘ and global PIL co-head Andrew Cannon is a specialist in advising states, state-owned entities and major companies on PIL matters; and at senior associate level, Hannah Ambrose, Aaron McDonald, Louise Barber and Marco de Sousa all act in investment arbitrations. Former partner Nick Peacock left the firm for Bird & Bird LLP in April 2021.

Latham & Watkins‘ ‘very knowledgeable and experienced group of individuals‘ advises on a range of PIL issues, including international boundary law and Law of the Sea disputes, investment treaty and international trade law, sanctions, and business and human rights. The firm also has an enviable investment arbitration practice. ‘Certainly in the top tier of law firm-based PIL experts‘, Charles Claypoole assists with investment treaty arbitration, international trade law, and state immunity matters; and Sebastian Seelmann-Eggebert, who divides his time between London and Hamburg, has a strong track record in international investment arbitrations. Also key to the group, Sophie Lamb KC consistently acts for corporate, financial, and sovereign entities in heavyweight international disputes; Robert Price (elevated to the partnership in January 2022) is an investment treaty arbitration expert; and associate Thomas Lane‘s practice covers international arbitration, international trade sanctions and export controls.

Quinn Emanuel Urquhart & Sullivan, LLP‘s London ‘team has made tremendous strides in the PIL space‘. The group has substantial experience in investment treaty arbitration and disputes (both for and against sovereign parties), its experience including investor-state claims under investment treaties, investment laws and investment contracts. The practice’s expertise also comprises large-value arbitrations involving the energy, oil and gas, mining, construction and infrastructure sectors. The names to note are: investment treaty arbitration expert Stephen Jagusch KC, the firm’s global international arbitration chair; Anthony Sinclair, ‘the real star of the practice‘; and Epaminontas Triantafilou, whose broad experience includes acting for both private corporations and sovereign governments. The second line of international arbitration specialists features Dominic Roughton, Mark McNeill, Julianne Hughes-Jennett and Alex Gerbi; and at senior associate level, Odysseas Repousis has particular expertise in investor-state disputes.

Three Crowns LLP‘s current investor-state caseload includes some of the highest-profile, most politically sensitive disputes in the world. ‘Probably one of the best arbitration practitioners of his generation‘, Constantine Partasides KC‘s track record includes obtaining large-value awards, with recent cases involving the Governments of Venezuela, Nigeria, South Korea and Vietnam; and Gaëtan Verhoosel routinely leads on high-value treaty arbitrations. Also integral to the practice are Middle Eastern disputes specialist Reza Mohtashami KC; Carmen Martinez Lopez, who works on substantial Latin American investor-state cases; and India expert Manish Aggarwal, whose practice also increasingly involves Singapore, Malaysia and Indonesia matters. Former counsel Leilah Bruton was made partner in January 2022, while Hamid Abdulkareem joined as counsel and Africa practice head in September 2021 from Nigerian firm Aluko & Oyebode, where he was partner. Key senior associate Farouk El-Hosseny acts in investor-state disputes in the telecoms and oil and gas sectors.

‘Experienced and knowledgeable across a wide range of PIL areas‘, Withers LLP‘s London PIL team has a highly active investor-state practice, representing both sovereign states, as well as foreign investors. The group also maintains a robust practice in international human rights litigation, state immunities, enforcement issues and sanctions. The team is jointly led by Hussein Haeri, ‘one of the top PIL experts working from a law firm‘; and consultant global counsel Sir Geoffrey Cox KC, the former Attorney General of England and Wales. The second line of key practitioners includes consultant Aniruddha Rajput, an expert in general international law, investor-state arbitration, boundary disputes, the Law Of The Sea and international trade law; special counsel Robert Kovacs, a specialist in PIL, international arbitration, and business and human rights; and senior associate Camilla Gambarini, who assists with PIL matters and investor-state arbitrations.

Baker Botts (UK) LLP‘s London team routinely handles large-value PIL disputes. It also advises on economic sanctions and export controls; energy and oil and gas sector matters; and cases involving Russia, Latin America and the Middle East. PIL chair Alejandro Escobar acts in investment protection treaty-related cases; Johannes Koepp has an active PIL and investor-state arbitration practice; Chris Caulfield is an economic sanctions and export controls specialist; Dorine Farah acts in investment treaty arbitrations; and senior associate Ernesto Féliz De Jesús is a Latin American disputes expert. Former partner Jay Alexander left to become an independent arbitrator in January 2022.

Carter-Ruck‘s international law team is widely praised for its expertise in advising clients who are the subject of targeted sanctions and restrictive measures at domestic, EU or international levels. International law head Guy Martin is ‘an outstanding international lawyer‘; senior partner Cameron Doley acts in cases before the United Nations, the European Court of Justice and the European Court of Human Rights; and Alasdair Pepper‘s client base includes companies, state heads and political figures. At senior associate level, Charles Enderby Smith advises on international sanctions, while François Holmey and Lawrence Northmore-Ball both act in large PIL cases.

Clyde & Co‘s PIL track record includes its representation of a Western Asian state, in relation to the oil and gas, transportation, international investment, telecoms and aviation sectors. The practice also advises on climate change and its interaction with fundamental human rights, along with trade and economic sanctions. Ben Knowles is global arbitration group chair; Maurice Kenton acts in investment arbitrations; Lee Bacon assists with LATAM-related disputes; and John Whittaker advises on investment claims, and sovereign immunity and sanction issues. Consultant Clare Hatcher is noted for international sanctions, while former partner Alejandro Garcia is now at Stewarts Law LLP.

DLA Piper‘s broad London PIL practice specialises not only in investor-state disputes, but also in advising states and companies on PIL issues. The group additionally assists with maritime boundary disputes, immunity issues and Treaty negotiations. The Brexit team is led by Paul Hardy; Kate Cervantes-Knox is an investor state arbitration expert; and John Forrest specialises in export controls, sanctions and international trade law. Also highly regarded are senior consultant Scott Horton, who is experienced in advising governments; London and Madrid-based of counsel Ben Sanderson, who ‘sees the big picture‘; and experienced legal director Elinor Thomas.

With ‘very extensive experience in advising states‘, Eversheds Sutherland (International) LLP‘s London PIL team has longstanding expertise in PIL work, and state-to-state and investor-state arbitrations. Global co-chair of international arbitration Jonathan Leach focuses on international commercial arbitration, investor-state arbitration and PIL matters; barrister Claire Stockford acts in investor-state arbitration claims; and Mark Howarth is experienced in state-state arbitrations. At principal associate level, Cameron Forsaith ‘has great breadth of knowledge‘, while Ahmed Abdel-Hakam is ‘a future star‘. Greg Falkof left the practice for Mishcon de Reya LLP in November 2022.

Gibson, Dunn & Crutcher‘s London office acts on a large number of investment treaty claims. The practice is co-led by the ‘excellent‘ Penny Madden KC, an expert in shareholder, telecoms and energy disputes, who also co-chairs the firm’s international arbitration group; and dual US/UK-qualified Cyrus Benson, who routinely acts before commercial and investment treaty tribunals. Also integral to the team is Jeffrey Sullivan KC, a specialist in both commercial and investment treaty arbitration, as well as the full range of PIL work. Sarah Wazen has now left the firm.

Hogan Lovells International LLP‘s London team routinely advises investors, states and state-owned entities on bilateral investment treaties, with particular experience in assisting clients emanating from the CIS and Eastern Europe. PIL and EU law specialist Markus Burgstaller regularly acts as an advocate in proceedings before international tribunals, the EU courts, the European Court of Human Rights, and national courts; and regularly working alongside Burgstaller, senior associate Scott Macpherson is experienced in PIL issues affecting the TMT and energy sectors.

Jones Day‘s ‘excellent‘ London office houses specialists in sanctions, Brexit issues, sovereign immunity, human rights, climate change and extradition, along with Interpol matters, maritime boundaries, state responsibility and treaty interpretation. The firm also has a widely respected investor-state arbitration practice. The ‘vastly experienced‘ PIL and arbitration specialist Michelle Bradfield was recruited in early 2021 from Dechert LLP; Sylvia Tonova routinely handles disputes across Europe, the Middle East, Asia, Africa and Latin America; and promoted to partner in January 2022, investor-state arbitration specialist Philip Devenish ‘has in-depth knowledge of public international law‘.

Linklaters LLP‘s PIL practice has a strong reputation for state-to-state disputes, international trade law, international human rights law and business and human rights advice. Additional key areas are investor-state disputes, state sovereignty, state immunity and intergovernmental organisations’ immunities. Global international arbitration chair Matthew Weiniger KC specialises in international arbitration and public international law, including international trade law; Charlotte Morgan is global co-head of trade law; Vanessa Havard-Williams co-leads the business and human rights group alongside Rachel Barrett; and Ben Carroll is energy disputes leader. Key managing associate Rebecca James assists with both international arbitration and international law matters.

Reed Smith LLP ‘has long experience in PIL matters, especially investment arbitration‘; and the practice fields sector specialists in energy, natural resources, construction, telecoms and banking. The group is jointly led by Belinda Paisley, whose experience includes a wide range of high-value arbitrations; and investment treaty arbitration and PIL expert Chloe Carswell. The second line of key advisers features Patrick Beale, who ‘can unravel very complex technical issues‘; and Ben Summerfield, who acts in investment treaty arbitrations. Recent growth includes Suzie Savage‘s elevation to partner and the promotion of ‘exceptional lawyer‘ Lucy Winnington-Ingram to senior associate.

Steptoe and Johnson UK LLP‘s London team routinely represents states and investors in PIL-governed arbitrations; and its expertise covers state-state disputes, state immunity laws in the UK and abroad, and anti-corruption laws and economic sanctions. Investment treaty arbitration chair Matthew Coleman is a go-to counsel for claims against African States; and Christophe Bondy has longstanding investment treaty arbitration experience. Promoted to partner in January 2022, Thomas Innes consistently acts in investor-state arbitrations; while masterful lawyer Juliya Arbisman is a 2021 recruit from Diamond McCarthy LLP for the London and New York offices. Associate Alexandre Genest also focuses on PIL work.

WilmerHale‘s London PIL practice is particularly well known for its representation in matters involving territorial boundaries and sovereignty over territory, including significant state-to-state matters, intra-state disputes, and high-value investor-state claims. The group also fields experts in the PIL issues that arise within the national courts, which involve transnational litigation and enforcement issues. The firm’s international arbitration practice is chaired by Gary Born, who has heavyweight experience as lead counsel in PIL disputes, including several investor-state arbitrations; and co-chair of the London office Steven Finizio is also highly active in PIL and investment treaty work.

With ‘a great track record in PIL matters‘, CMS has extensive experience in international disputes and advisory work. PIL team head Karen Denny is ‘an outstanding lawyer‘, and Edinburgh-based Pieter Bekker leads the firm’s investment arbitration task force. Sarah Vasani joined as international arbitration co-head from Addleshaw Goddard in September 2021.

Curtis, Mallet-Prevost, Colt & Mosle LLP routinely represents sovereign nations in investor-state arbitrations. The experience of PIL leader Charles Buderi covers both international arbitration claims involving states, and the representation of governments in relation to sovereignty disputes, and treaty and diplomatic matters; and Luciana Ricart frequently advises states and state-owned entities.

King & Spalding LLP‘s department specialises in inter-state disputes involving territorial disputes, privileges, immunities, and international human rights. The team is also experienced in international and transnational criminal law, investment law, and the Law of the Sea. Group head Ben Emmerson KC is a PIL and international corporate risk management specialist.

King & Wood Mallesons‘ track record includes successful state-side defences against investor claims in the real estate, energy, banking, telecoms, mining and natural resources sectors. Andrei Yakovlev acts in disputes involving M&A, foreign investment, and sovereign and corporate finance; and Wilson Antoon ‘has a lot of experience in working for states‘.

Peters & Peters Solicitors LLP‘s PIL practice covers sanctions, extradition, and INTERPOL, ECHR and arbitration court representations. The principal figures are former CPS extradition head Nick Vamos; criminal law practitioner Michael O’Kane; international sanctions expert Anna Bradshaw; financial crime specialist Neil Swift; and former Extradition Lawyers’ Association chair, Jasvinder Nakwal.

Stephenson Harwood‘s practice acts for state entities and state-owned companies, and houses experts in financial sanctions. Practice head Kamal Shah also leads the Africa and India groups; Ben Sigler is ‘an insightful lawyer‘; and Sue Millar, Richard Garcia and of counsel Stephen Ashley have ‘great knowledge of PIL issues‘.

The track record of White & Case LLP‘s London team includes representing large numbers of sovereign states, state-owned entities, and private and commercial parties in matters involving PIL issues. Global PIL head Andrea Menaker is an investment treaty arbitration specialist, while David Goldberg represents sovereign states in high-value investor-state disputes.