Lionel Nichols and Emile Simpson Appointed to Attorney General’s Public International Law Panel
Four New Square Chambers are delighted to announce the appointment of two…
Lionel Nichols is a leading junior specialising in international and cross-border disputes, with a practice spanning commercial litigation, international arbitration and public international law, including jurisdiction and conflict-of-laws issues. He is regularly instructed in high-value, complex matters for States, corporations and individuals before English courts and international tribunals.
Lionel initially qualified as a solicitor in Australia in 2008, practising in commercial litigation at an international law firm in the UK and becoming a partner before transferring to the English Bar in 2013, and brings a solicitor’s collaborative and commercial perspective.
Lionel graduated with a triple first (Law, Politics, and Philosophy) and a Master of International Politics from the University of Tasmania before being awarded a Rhodes scholarship to study at the University of Oxford where he graduated with a Bachelor of Civil Law, a Master of International Politics and a Doctor of Philosophy in Law.
Lionel also sits as an arbitrator and is a Fellow of the Chartered Institute of Arbitrators.
A selection of Lionel’s experience is provided below. More comprehensive information is available on request.
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Lionel has a broad international arbitration practice encompassing complex, high-value commercial disputes across multiple areas, including financial services, energy, insurance, shipping and civil fraud. His work frequently involves cross-border disputes with parallel proceedings, and he is experienced both as part of counsel teams and as sole counsel.
He is regularly instructed in arbitrations seated in major arbitral centres worldwide, including proceedings under the CIArb, HKIAC, ICC, ICSID, LCIA, SCC, SIAC and UNCITRAL Rules, as well as ad hoc arbitrations. His practice covers banking & financial services, commodities and international trade, and energy & infrastructure, with a focus on Africa, CIS & Russia, and offshore jurisdictions. He has also advised claimants and States in relation to potential claims under bilateral and multilateral investment treaties.
His experience spans the full lifecycle of disputes, from pre-arbitration strategy and pleadings through to evidential hearings and post-award challenges and enforcement. His clients include multinational corporations, financial institutions and high-net-worth individuals, and he is accustomed to working on large-scale disputes involving complex factual and legal issues.
Alongside his arbitration practice, he has significant experience of arbitration-related litigation before the English courts, including challenges to awards, applications for interim relief and enforcement proceedings. He has particular expertise in applications under the Arbitration Act 1996, including challenges under sections 67, 68 and 69, stays of proceedings under section 9, freezing injunctions under section 44 and determinations of jurisdiction under section 32
Featured International Arbitrations as Counsel
Arbitration Experience
Court-Related Arbitration Experience
Featured Arbitral Appointments
Lionel has sat as arbitrator in many arbitrations, both as sole arbitrator and as part of a panel. He is a Fellow of the Chartered Institute of Arbitrators and a member of the London Court of International Arbitration.
Selected appointments include:
Lionel practises in commercial litigation, with a focus on High Court cases involving complex, international and multi-jurisdictional disputes. His experience spans finance, civil fraud, company disputes and a broad range of general commercial matters, including:
He is instructed both as sole counsel and as part of larger teams, and is experienced in managing complex litigation from early-stage applications through to trial.
Featured Commercial Litigation Cases
Lionel is one of London’s most experienced juniors in public international law. His broad practice covers all aspects of public international law for individuals, NGOs and States, including:
On 1 January 2026, Lionel was appointed to the Attorney General’s ‘B’ Panel for Public International Law for a five-year term.
Lionel was Geoffrey Robertson KC’s first-choice junior on all aspects of public international law. In addition to casework, Lionel provided research assistance on numerous academic titles, including Crimes against Humanity, The Case of the Pope, An Inconvenient Genocide, Mullahs Without Mercy and Who Owns History?
He holds two master’s degrees in international law, a master’s degree in international relations, and a doctorate in international law which was examined by Professor Dapo Akande. Prior to joining Chambers, Lionel was the Global Justice Research Fellow at the University of Oxford. He has published widely in the field of public international law and is regularly invited to speak at conferences. He is the author of The International Criminal Court and the End of Impunity in Kenya.
Lionel advises the Norfolk Island Government in its attempts to obtain the status of a non-self-governing territory under Chapter XI of the United Nations Charter.
Selected Public International Law Experiences
International Court of Justice
United Nations Human Rights Committee
International Criminal Law
European Court of Human Rights
African Commission on Human and Peoples’ Rights
Investment Treaty Arbitrations
Domestic Courts
Lionel’s extensive experience in commercial litigation, human rights, public international law and private international law places him well to act on ESG, business & human rights and climate change matters. His experience includes:
Selected experience includes:
Selected ESG publications include:
Lionel has also served as an expert reviewer in a comparative study conducted by the University of Oxford’s Bonavero Institute of Human Rights on civil liability for human rights violations across 18 jurisdictions.
Lionel regularly advises on sanctions issues across the UN, EU and UK frameworks, particularly in relation to financial sanctions and export controls. He also advises on potential sanctions challenges.
Selected experience includes:
Lionel has experience in company and insolvency litigation, particularly matters with an international or offshore dimension, and is regularly instructed to appear in the Insolvency & Companies Court.
His work includes corporate and personal insolvency, including administration, bankruptcy, liquidation, winding-up petitions and applications to set aside statutory demands, as well as shareholder disputes, unfair prejudice petitions, derivative claims, litigation arising from corporate transactions, corporate governance and directors’ duties.
Selected experience includes:
Legal 500“His quick understanding and appreciation, thoughtful questions, careful explanations, clever and clear drafting, and collaborative approach to the development of case strategy are impressive.”
Legal 500
Commercial Litigation
Fellow of the Chartered Institute of Arbitrators
Member of the London Court of International Arbitration
DPhil in Law (University of Oxford)
MPhil in Law (Dist.) (University of Oxford)
BCL (University of Oxford)
Master of International Politics (University of Tasmania)
Bachelor of Laws (1st) (University of Tasmania)
Bachelor of Arts (1st) (University of Tasmania)
Rhodes Scholarship, Commonwealth Scholarship, Tim Hawkins Memorial Scholarship
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