Allen & Overy LLP has superlative expertise across the full spectrum of public international law and related matters ranging from environmental and human rights issues to transnational jurisdiction, international compliance and sanctions issues. Its 'outstanding and hardworking' team is experienced in state-to-state disputes before the International Court of Justice and tribunals under the jurisdiction of the Permanent Court of Arbitration, ICSID, the United Nations Convention for the Law of the Sea and other ad hoc bodies. The group's capabilities in human rights law was bolstered by the arrival of Suzanne Spears from Volterra Fietta; she handles advisory and contentious work, with a focus on matters related to investment treaties, territorial boundaries, international trade and sovereign immunity. Mark Levy QC regularly coordinates with the Paris office in representing sovereign state and corporate clients in commercial arbitrations and investment treaty cases. Other key figures include Kate Davies and James Freeman and senior associates Naomi Briercliffe and Guled Yusuf. 

Clifford Chance LLP has significant bench strength in international investment arbitration, as well as in complex and politically sensitive issues in the field of public international law; its team has recently advised on claims to self-governance by constituent territories within states and the application of human rights law within territories under occupation. The practice has also seen a growth in Brexit-related instructions, such as advising on the implications of restrictions on foreign investment; alternative EU membership models; and inbound and outbound trade-law issues post-Brexit. Recent work for practice heads Audley Sheppard and Rae Lindsay includes acting for the claimants in substantial investment treaty proceedings against various states; advising on issues arising in territories in conflict and/or under occupation; and assisting with matters concerning human rights law. Jessica Gladstone advises corporate clients, international organisations and states on WTO rules (including state aid rules and subsidies issues), as well as on international sanctions.

Debevoise & Plimpton LLP has 'unmatched breadth of experience' across a broad spectrum of public international law-related areas. The team regularly undertakes complex cases involving international environmental law; international humanitarian law; treaty interpretation; indigenous rights; arbitrary detention; political persecution; state responsibility for internationally wrongful acts; and denial of justice claims. Lord Peter Goldsmith is particularly noted for his substantial experience in representing sovereign and commercial clients in public international law arbitration and other court proceedings worldwide. He is currently lead counsel in a series of high profile public international law disputes pursued by the State of Qatar, including in its case before the International Court of Justice under the International Convention on the Elimination of All Forms of Racial Discrimination. Wendy Miles and Patrick Taylor are the other key names for proceedings in the financial services, telecoms, construction, and energy and natural resources sectors. Aimee-Jane Lee advises on the international protection of investments, particularly under bilateral investment treaties, the Energy Charter Treaty and investor-state contracts.

Arguably, 'one of the leading boutique practices in public international law', Fietta LLP has substantial expertise in investment treaty proceedings, maritime boundary disputes and human rights matters. The practice is regularly instructed by sovereign states, corporate, individual and NGO clients across a wide spectrum of public international law matters. Stephen Fietta QC has 'an outstanding reputation' in investment treaty arbitration and often leads on high-profile and substantial claims, including acting for a large group of Greek investors in an ICSID arbitration against the Republic of Cyprus arising from the Cypriot financial crisis and European Union/IMF bail-out of 2013. Also of note are recently promoted partner Jiries Saadeh, counsel Ashique Rahman and associates Oonagh Sands and Laura Rees-Evans.

Freshfields Bruckhaus Deringer LLP's public international law team stands 'head and shoulders above its peers'. The group has extensive experience in acting for states in inter-state disputes, international investment arbitration and proceedings in the International Court of Justice, the European Court of Justice and Human Rights, and other specialist international tribunals, including under the UN Convention on the Law of the Sea. It also advises clients on complex contentious and non-contentious sanctions issues globally, and continues to work with international organisations where it is advising on the UN Guiding Principles on Business and Human Rights. The team also advises global lenders, development banks, and other international organisations on the immunity of international organisations under international law. Will Thomas has particular expertise in the energy, telecoms and projects sectors, with a focus on disputes in the Middle East and Africa. Sylvia Noury focuses on investor-state disputes in emerging markets, particularly in Africa, India and Latin America.

Volterra Fietta is a boutique practice focusing entirely on public international law. The team has 'a very good reputation' as counsel and advocates at the International Court of Justice, the European Court of Human Rights and tribunals constituted under the auspices of the Permanent Court of Arbitration, ICSID and United Nations Convention for the Law of the Sea. The practice advises a mix of states, international organisations and corporate clients on bilateral investment treaties; land and maritime territorial and boundary disputes; treaty interpretation; state responsibility; sovereign and diplomatic privilege and immunity; economic sanctions; international environmental law; and international trade and WTO law. Key figures include name partner Robert Volterra, Graham Coop and international counsel Álvaro Nistal.

At Cooley (UK) LLP, Tim Daniel is noted for his work with a number of governments and parastatals, particularly in the developing world. Key mandates include representing various states before the ICJ in a number of significant land and maritime boundary disputes. Daniel's practice also covers counter‐terrorism and asset tracing for states and private companies; he continues to advise the government of Nigeria on national and international boundaries. James Maton and Laurence Harris act for corporations and governments in a wide range of complex commercial, regulatory and public international law disputes, with a focus on the recovery of proceeds of corruption and enforcing foreign confiscation orders. John Brown is an expert in maritime boundary delimitation and in the definition of maritime zones. Counsels Christophe Bondy and Joshua Brien are also of note for investment-state arbitration, Law of the Sea matters and for issues concerning the continental shelf.

Herbert Smith Freehills LLP's team of 'top-tier lawyers' has 'excellent experience' in investment treaty arbitration, acting for sovereign and leading multinational clients in proceedings against states. The group's work in this space focuses strongly on disputes in areas where the firm is traditionally strong, including the energy, oil and gas, mining and banking sectors. Other areas of expertise include Law of the Sea issues, sovereign and international organisation immunity and human rights-related matters, sanctions and international trade law; the team has also been seen a steady growth of work advising clients on the UK's exit from the EU. Andrew Cannon has 'tremendous experience in public international law'. Iain Maxwell is noted for his representation of clients in ICSID investment arbitration.

Latham & Watkins fields 'a talented team of lawyers' with 'first-class' knowledge of public international law ranging from territorial boundary law, maritime delimitation to Law of the Sea disputes before the International Court of Justice and the Permanent Court of Arbitration; international trade and WTO law; sovereign immunity; international humanitarian law and human rights. Its international sanctions practice continues to be sought for advice related to sanctions imposed against Russia and it has noted a steady growth in instructions relating to international sanctions on Iran and EU blocking measures. Charles Claypoole has a strong track record as an advocate in investment treaty arbitration, and is currently representing Ukraine in the largest treaty claim brought against it, valued at approximately $5bn. Sophie Lamb and Sebastian Seelmann-Eggebert are also highly regarded for international arbitration.

Quinn Emanuel Urquhart & Sullivan, LLP is best known for for its 'solid reputation' in the field of international arbitration and disputes arising under contracts and bilateral or multilateral investment treaties. Its disputes team, led by Stephen Jagusch QC, has extensive experience in investment treaty arbitration under ICSID and UNICITRAL rules, particularly those involving the oil and gas, mining, energy, telecoms, construction and infrastructure sectors. Jagusch is 'one of the preeminent lawyers in public international law' and a highly experienced counsel and advocate who has acted for sovereign states and multinational corporations in all of the major arbitral forums. Anthony Sinclair specialises in investment treaty arbitration and disputes involving the Energy Charter Treaty. Epaminontas Triantafilou and Alex Gerbi are other key partners.

Skadden, Arps, Slate, Meagher & Flom (UK) LLP's combined expertise in contentious and non-contentious international law makes it a popular choice for sovereign states and private entities alike for representation in major investment treaty arbitration, especially under ICSID rules, as well as for advice on treaty interpretations, state succession, international economic sanctions and human rights issues. The practice is jointly headed by David Kavanagh, who is 'a distinguished figure in international arbitration', and Karyl Nairn, who is a specialist in private and public international law. David Herlihy, Bruce Macaulay, Daniel Gal and Nick Lawn make up the other key practitioners in the 'outstanding and dedicated team'.

Focusing exclusively on dispute resolution, Three Crowns LLP fields 'a very strong team with unparalleled expertise' in international arbitration and public international law. It further expanded its offering through the hire of Reza Mohtashami QC from Freshfields Bruckhaus Deringer LLP in November 2018, adding complementary expertise in disputes arising in emerging markets and in the telecoms, energy and infrastructure sectors. The team regularly represents sovereign states, government-owned entities, commercial clients and private entities, both as claimants and respondents, in all major commercial arbitration rules such as ICSID, ICC and UNCITRAL. Constantine Partasides QC's recent mandates include acting as leading counsel for sovereigns in ICSID disputes, and also acing for clients in investment treaty claims against sovereigns and state entities in Venezuela, Vietnam and the Republic of South Korea. Also of note are Gaëtan  Verhoosel, who is 'a well-known figure' in investor-state arbitration, and recently promoted partner Manish Aggarwal.

Arnold & Porter has 'a very good reputation in the public international law sphere' where its advises on investment treaty arbitration under the ICSID Rules, UNCITRAL investment treaty arbitrations conducted under the auspices of the Permanent Court of Arbitration in The Hague, and other ad hoc arbitration rules. The practice continues to expand in personnel and client numbers; it was recently bolstered by the hire of Jane Wessel from Shepherd and Wedderburn and has received new instructions from the European Commission and Latin American clients.  Dmitri Evseev's work focuses on acting for sovereign states in investor-state arbitrations under various bilateral investment treaties and the Energy Charter Treaty; Patricio Grané Labat leads on Latin American investor-state cases. David Reed is another name to note.

Baker Botts (UK) LLP has significant investor-state arbitration expertise, particularly under ICSID rules as well as UNCITRAL investment-treaty arbitration. The London team is also able leverage complementary expertise in international financial sanctions from the firm's US and Brussels teams. Its caseload spans a wide variety of industry sectors, particularly oil and gas, telecoms and banking. Chris Caulfield has considerable experience in the field of economic sanctions and export control. Alejandro Escobar is a 'superb lawyer' for highly complex and substantial investment treaty arbitration.

Boies Schiller Flexner (UK) LLP's team of 'first-rate dispute resolution lawyers' has 'a wealth of experience' in investor-state claims and sanctions, while also advising on the non-contentious core issues of public international law, including maritime and land boundary disputes; Law of the Sea issues; state succession; state responsibility; treaty interpretation and human rights law. Dominic Roughton, who is 'an excellent lawyer with sound judgement', has significant investment treaty expertise. Other key figures include investor-state experts Kenneth Beale and Natasha Harrison.

Carter-Ruck's team is particularly experienced in relation to sanctions or restrictive measures imposed at UN, EU or domestic level, and often represents clients before the UN Ombudsperson, the European Court of Justice, and in domestic judicial reviews of administrative decisions relating to sanctions. Guy Martin 'is the one of the foremost legal experts on sanctions'; he is representing Saudi businessman and philanthropist Yassin Kadi in his longstanding battle to challenge sanctions imposed on him in October 2001. Other key clients include governments, heads of state and leading political figures, commercial entities, charities and high-profile private clients.

Clyde & Co LLP advises on both the contentious and non-contentious facets of public international law ranging from investor-state arbitrations and territorial boundary disputes to economic sanctions and diplomatic immunity. It also has extensive experience dealing with highly sensitive cross-border disputes for claimants and respondents within emerging markets. John Whittaker leads on investment disputes, sovereign immunity and sanction matters, particularly in cases involving sanctions in Iran and Syria. Co-chair of the global arbitration group Ben Knowles has 'a very good grasp of the core issues in public international law'.

Eversheds Sutherland (International) LLP's investor-state arbitration practice continues to be highly sought after by states in the most significant disputes. It is acting for the state of Libya in its defence of three separate and unrelated arbitrations, brought in the aftermath of the Arab Spring.  The group also draws upon its network of international offices to advise on treaty obligations and interpretation, the status of foreign governments, state immunity, and international human rights claims. Jonathan Leach advises multinational corporates on non-contentious and contentious matters arising from their investments into and trade with emerging markets. Other key figures to note include Mark Howarth, who is representing the Islamic Republic of Iran in a long-running dispute with the USA, before the Iran-US Claims Tribunal; Greg Falkof, and senior associates Cameron Forsaith and Ahmed Abdel-Hakam.

At Linklaters LLP, Matthew Weiniger QC leads 'a very talented team with vast amounts of experience' in advising clients on their substantive and procedural rights under investment treaties, as well as expertise in serving as lead counsel in bilateral investment treaties and other investment disputes across a variety of industry sectors, including telecoms, energy and utilities. The group is also able to draw on experts in trade law, WTO policy and regulations; state and diplomatic immunity; human rights law and corporate responsibility; and its sanctions team advises clients on contentious multi-jurisdictional issues, most recently in relation to sanctions frameworks aimed at Russia/Ukraine, Iran, Iraq, Syria and Libya. Lorand Bartels has extensive practical experience in trade law, especially free trade agreements.

Focusing on investment-state disputes, Simmons & Simmons continues to be actively involved in arbitration proceedings in the telecoms, financial services, energy and infrastructure sectors across Europe, the CIS, Asia and Africa. Stuart Dutson chairs the international arbitration group and has 'very good specialist knowledge of public international law'. Jayne Bentham specialises in international arbitration in the telecoms and energy sectors.

Steptoe and Johnson UK LLP has significant courtroom experience as counsel for investors, sovereign states and inter-governmental organisations in investor-state arbitration, disputes before the WTO Appellate Body and the International Tribunal for the Law of the Sea. The practice also has extensive experience with the jurisdictional immunities of sovereign states. Matthew Coleman is particularly experienced in investment arbitration concerning African, Eastern European and Caribbean cases, and is often supported by associate Thomas Innes.

Wilmer Cutler Pickering Hale and Dorr LLP has significant experience of complex and politically sensitive disputes involving territorial boundaries and sovereignty over territory, particularly in the Middle East and Africa. The practice also regularly advises sovereign states on key issues of international law, including treaty accession, territorial boundaries, maritime delimitation, international criminal law and human rights. Gary Born chairs the the firm's sizeable international arbitration group and frequently leads counsel on state-to-state, investor-state, ICSID and ad hoc international arbitration tribunals. Steven Finizio is a name to note for public international law as it applies to small states.

Withers LLP's public international law practice was strengthened by the arrivals of consultant Aniruddha Rajput, who is a member of the UN International Law Commission, and senior associate Robert Kovacs, who joined from Volterra Fietta and has broad experience in public international law, human rights and international arbitration. The practice advises sovereign governments, multinational companies and individuals on matters ranging from international investment law, human rights, sanctions, WTO law, maritime law and state immunities. Hussein  Haeri is an experienced advocate in state-state and investor-state disputes and arbitrations under the auspices of the PCA, UNICTRAL and ICSID.

Baker McKenzie has significant experience acting for corporations and investors in disputes against states and state-owned entities in investment treaty arbitration under UNCITRAL and ICSID rules. The practice has a notable focus on disputes involving oil and gas, acting for oil majors, service providers, and sovereign states and entities. Edward Poulton focuses on investment-related arbitration and also advises on public international law issues arising from financial crises, regulatory changes or international instruments.

CMS' key strengths lie in investor-state arbitration and investment treaty arbitration. Karen Denny advises states on sovereign immunity and related matters including sovereign privileges and inviolability; Pieter Bekker chairs the firm's investment arbitration task force and has significant courtroom experience of investment treaty arbitrations acting on behalf of claimants and respondents; and Christopher Gooding represents states, state-owned companies and claimants in disputes which are at the interface between public and private international law.

Curtis, Mallet-Prevost, Colt & Mosle LLP's public international practice acts exclusively for sovereign clients in investor-state international arbitration and inter-state disputes. The team has a niche working with countries from emerging markets. On the non-contentious side, Charles LO Buderi is experienced in advising governments on sovereignty, treaty and diplomatic issues, as well as on other public international law matters.

Dentons leverages strong combined expertise from its network of international offices in investor-state arbitration, particularly under ICSID rules as well as in UNCITRAL proceedings, and also advises on broader public international law issues such as treaty interpretation, sovereign immunity, state succession, sanctions and human rights law. Liz Tout has particular expertise in disputes relating to energy and natural resources. Senior associate Catherine Gilfedder 'is a very strong practitioner in the field'.

Gibson, Dunn & Crutcher acts for a mix of sovereign and corporate clients, including Yukos Capital amd Global Telecom, in investment treaty arbitration, particularly under ICSID auspices. Its team also works on high-profile pro bono initiatives, including on behalf of Nazanin Ratcliffe, who has been imprisoned by the Iranian Revolutionary Guard. Cyrus Benson, Jeffrey Sullivan and Penny Madden QC are all highly accomplished partners.

Jones Day has a strong track record in investor-state arbitration involving high-profile individuals, corporations, sovereigns and sovereign entities. International arbitration partner Baiju Vasani is also experienced in advising states on the negotiation and drafting of treaties and has worked with the government of Somalia to assist with its accession to the New York Convention on the Recognition and Enforcement of Foreign Arbitral Awards. Lee Coffey, Sylvia Tonova and Tatiana Minaeva are other names to note.

King & Wood Mallesons primarily focuses on investment arbitration, acting on behalf of investors and state governments under ICSID and UNCITRAL rules. Dorothy Murray has expertise working for clients from China, Russia and the CIS. Andrei Yakovlev splits his time between London and Dubai and focuses on acting for sovereign states, central banks, corporate and private clients in investor-state and commercial arbitration.

Peters & Peters Solicitors LLP has developed 'very good' expertise across the full range of economic sanctions issues, including challenging sanctions in court, defending clients accused of breaching sanctions and advising corporations on sanctions compliance. The practice also represents governments and investors in ICSID and other investor-state arbitral forums. Michael O’Kane leads the public international practice and has 'a superb reputation' acting for investors in challenging the decisions of states through arbitration, advising on EU sanctions and representing clients facing human rights violations. Nick Vamos is highly experienced in international criminal law, especially from the side of the prosecutor; Jasvinder Nakwal is a name to note for cases involving human rights violations.

At Reed Smith LLP, Belinda Paisley heads the London team, which primarily handles investor-state matters. Chloe Carswell frequently supports Paisley in complex and high-value investment treaty arbitration under the rules of the ICC, ICSID and UNCITRAL. The duo also have significant asset tracing expertise, assisting states and private entities.

Stephenson Harwood combines 'second-to-none' expertise in international sanctions and enforcement issues with its work representing governments and state-owned companies in investment treaty and investor-state disputes. Department head Kamal Shah has strong experience in Africa and India-related arbitration. Sue Millar advises on a range of contentious and non-contentious issues arising in relation to the various Iranian, Libyan, Syrian and Russian sanctions regimes. Richard Garcia and senior associate Stephen Ashley are 'superb lawyers in the sanctions and public international law sphere'.