Mark Wassouf

“He is fantastically smart but also extremely practical and has a great deal of commercial common sense.” Legal500 2025 (Commercial Litigation)

Mark is regularly instructed either as sole counsel or as part of a counsel team on a range of complex commercial disputes. Highlights of Mark’s commercial litigation practice include:

• Acting, as sole counsel, for a large Middle Eastern company challenging an ICC award pursuant to ss.67 and 68 of the Arbitration Act 1996. The proceedings involve difficult legal and procedural questions, including an argument that the award is contrary to English public policy by virtue of the nature of the underlying contract.
• Acting for a Middle Eastern state in its ongoing challenge to an investment treaty award under s.67 of the Arbitration Act 1996 (led by Christopher Harris KC and Laurence Rabinowitz KC).
• Acting for the Russian Federation on five ongoing litigations in the Commercial Court, including in its resistance to the enforcement of the US$50 billion Yukos award before the English courts.  The 2025 judgment of the Court of Appeal in the same case (Hulley v Russia [2025] EWCA Civ 108) is the leading authority on state immunity and issue estoppel and may be found here.  Likewise, the 2021 judgment of Mr Justice Henshaw in the Hulley case (Hulley v Russia [2021] EWHC 894 (Comm)), is considered one of the leading judgments on s.103 of the Arbitration Act 1996 and its interplay with state immunity issues, may be read here.
• Acting for the claimant in McCarthy v Proctor [2025] EWHC 25 (Ch), on a strike out / summary judgment application involving questions of acknowledgment / part payment for purposes of the Limitation Act 1980.  The judgment in that case may be read here.
• Acting for Zhongshan in Zhongshan Fucheng Industrial Investment Co v The Federal Republic of Nigeria [2024] EWHC 1503 (available here) in proceedings to enforce a US$60 million investment treaty award in England (led by Christopher Harris KC).  That case went up to the Court of Appeal in June 2023 on the question of whether the approach adopted by the English Court to the grant of enforcement orders satisfied its obligations under s.1(2) of the State Immunity Act 1978.  The Court of Appeal’s judgment on that point (finding in favour of Mark’s client) may be read here.  In June 2024, Zhongshan was successful on an application for charging orders over two properties in Liverpool, owned by Nigeria – the relevant judgment may be read here.  That judgment is a rare example of successful enforcement in the face of a diplomatic certificate asserting immunity pursuant to s.13(5) of the State Immunity Act 1978.
• Acting, as sole counsel, for the successful claimant on a strike out / summary judgment application related to a loan of approximately  in Yamada Limited v Setara Holdings  [2024] EWHC 3095 (Comm).  The judgment may be read here.  In that case, the defendants put up a complex and long defence making wide ranging allegations based on misrepresentation, implied terms, set-off, the application of the Unfair Contract Terms Act 1977 and other matters.  The Court accepted Mark’s submission that, superficial complexity notwithstanding, that defence had no prospect of succeeding.
• Acting for the defendant (investor) in The Federal Republic of Nigeria v Zhongshan (2021), which was a rare example of a challenge to an investment treaty award under s.67 of the Arbitration Act 1996.  That application was abandoned by Nigeria before trial.
• Acting for Frasers Group PLC in a long running litigation against Saxo Bank AS and Morgan Stanley arising from a billion-dollar margin call.  The case concerned difficult legal questions as to the scope of Braganza duties and the economic torts.  It has resulted in numerous interlocutory applications, several of which have resulted in reported judgments.  The case was heard at a three-week trial in February and March 2024 (led by Adrian Beltrami KC).
• Acting for a large Brazilian natural resources company in an application for urgent injunctive relief under s.44 of the Arbitration Act 1996 in support of putative arbitral proceedings (led by Peter de Verneuil Smith KC).
• Acting, as sole counsel, for the European Bank for Reconstruction and Development (EBRD) in a EUR 9 million claim concerning breach of the terms of an agreement for the funding of a substantial hydropower project in Albania.  Mark successfully obtained summary judgment for the EBRD in respect of the whole amount.  The reported judgment may be read here (instructed by Bird & Bird as sole counsel).
• Acting, as sole counsel, for a Danish company in response to a letter of request made by the Danish court for witness evidence to be taken in England.  The reported judgment in that case (which is cited in commentary as an important authority on the Evidence (Proceedings in Other Jurisdictions) Act 1975) may be read here.

Mark has also appeared, either led or as sole counsel, in the context of numerous banking and finance-related disputes in the County Courts and High Court, including matters involving commercial contracts, PPI claims, guarantees and the sale of goods. Mark frequently appears as counsel in procedural hearings, trials and in the full range of applications.

“Mark Wassouf is very thorough and he really fights his client’s corner” Chambers 2025

Mark has become particularly recognised for his expertise in arbitration-related court applications.  He is frequently instructed, either as lead counsel or as part of a counsel team, in a broad range of applications under the Arbitration Act 1996 and has acted both for parties enforcing awards as well as resisting their enforcement.  Current and recent highlights include:

• Acting, as sole counsel, for an international conglomerate in an action to enforce an investment treaty award against a Latin American state.
• Acting, as sole counsel, for a large Middle Eastern company challenging an ICC award pursuant to ss.67 and 68 of the Arbitration Act 1996. The proceedings involve difficult legal and procedural questions, including an argument that the award is contrary to English public policy by virtue of the nature of the underlying contract.
• Acting, as sole counsel, for an Ivorian trading company in its challenge to a GAFTA award under ss. 67 and 68 of the Arbitration Act, including in relation to its application for an extension of time in which to bring that challenge pursuant to s.70(3) of the Arbitration Act 1996.
• Acting for a Middle Eastern state in its challenge to an investment treaty award under s.67 of the Arbitration Act 1996 (led by Christopher Harris KC and Laurence Rabinowitz KC).
• Acting for the Russian Federation in its resistance to five separate ongoing enforcement proceedings before the Commercial Court in which Russia is resisting the enforcement of investment treaty awards, notably Hulley v Russia [2025] EWCA Civ 108; and JSC DTEK Krymenergo v Russia [2025] EWHC 1060 (Comm). All five cases involve an attempt to enforce an arbitration award pursuant to s.101 of the Arbitration Act 1996, and the assertion by Russia of immunity under s.1 of the State Immunity Act 1978.
• Acting for the successful claimant (investor) in an action for enforcement of an investment treaty award in England pursuant to s.101 of the Arbitration Act 1996 (Zhongshan Fucheng Industrial Investment Co Ltd v Federal Republic of Nigeria [2024] EWHC 1503 (Comm)) (led by Christopher Harris KC).  In June 2024, Zhongshan was successful on an application for charging orders over two properties in Liverpool, owned by Nigeria – the relevant judgment may be read here.  That judgment is a rare example of successful enforcement in the face of a diplomatic certificate asserting immunity pursuant to s.13(5) of the State Immunity Act 1978.
• Acting for a large Brazilian natural resources company in an application for urgent injunctive relief under s.44 of the Arbitration Act 1996 in support of putative arbitral proceedings (instructed by Mayer Brown and led by Peter de Verneuil Smith KC).

“Mark has an impressive understanding of public international law as well as clear and persuasive drafting.” Legal 500 2024

“Mark Wassouf is clear, concise and extremely well versed in the landscape of bilateral investment treaties.” Chambers 2024

Mark has acted as counsel (both to claimants and to respondent states) in over a dozen investment treaty arbitrations. He is regularly instructed to assist with written and oral submissions in complex investment claims and is recognised in the directories as a leading barrister for international arbitration.

Recent highlights of Mark’s investment treaty arbitration practice include:

• Qatar Pharma and Al Sulaiti v Kingdom of Saudi Arabia – Mark acts as counsel to the Kingdom of Saudi Arabia in this US$400 million claim under the OIC Agreement in relation to a pharmaceuticals business (led by Christopher Harris KC).
• Viaduct and ors. v Bosnia and Herzegovina (ICSID Case No. ARB/16/36) – Mark acted as counsel to the claimants in a US$70 million ICSID claim relating to a renewable energy investment (led by Christopher Harris KC).  Mark has continued to act as counsel in relation to annulment proceedings at ICSID.
• Carlyle v. Kingdom of Morocco (ICSID Case No. ARB/18/29) – Mark acted as counsel to the Kingdom of Morocco in a US$ 400 million ICSID claim brought by U.S. claimants relating to the insolvency of a major refinery (led by Christopher Harris KC, 3VB).
• Alexander Nelin v. Republic of Cyprus (ICSID Case No. ARB/18/41) – Mark acted for the claimant in this ICSID investment treaty arbitration concerning the loss of significant cash deposits following state intervention in a bank in Cyprus (led by Christopher Harris QC, 3VB).  The case was discontinued following the tragic death of the claimant.
• KLS Energy v Democratic Socialist Republic of Sri Lanka (ICSID Case No. ARB/18/39) – Mark acted for the claimants in this ICSID investment treaty arbitration arising out of a project in the renewable energy sector. The case concerns, amongst other things, the state’s refusal to abide by contractual obligations and involves questions of attribution under international law (led by Christopher Harris QC, 3VB).
• Czech investor v European State (UNCITRAL) – Mark acted for the claimant in this UNCITRAL investment treaty arbitration in the gaming sector, involving the indirect expropriation of the Claimant’s business by virtue of a change in the host state’s law. The case also involved detailed argumentation on the implications of the CJEU’s judgment in Achmea (led by Christopher Harris KC, 3VB).
• Attila Doğan Construction & Installation Co. Inc. v. Sultanate of Oman (ICSID Case No. ARB/16/7) – Mark acted for the respondent in this ICSID investment treaty arbitration involving, amongst other things, complex questions on attribution under international law (instructed by Three Crowns LLP).
• Marfin Investment Group Holdings S.A., Alexandros Bakatselos and others v. Republic of Cyprus (ICSID Case No.ARB/13/27) – Mark acted for the claimant in this ICSID investment treaty arbitration in connection with the demise of Cyprus’s second largest bank. The case also involved detailed argumentation on the implications of the CJEU’s judgment in Achmea. Award issued in mid-2018 (led by Tariq Baloch, 3VB and instructed by Three Crowns LLP).

Mark is also frequently instructed to assess the merits of potential investment treaty claims. He has provided merits analyses to potential claimants considering whether to launch a claim, as well as to arbitration funders.

“Mark Wassouf is a very impressive junior. He’s very good with solicitor and client relationships, and his legal advice is top notch.”  Chambers 2025

“A confident, very dedicated and accomplished advocate.” Legal500 2025

Mark has acted as counsel in numerous commercial arbitrations conducted under the rules of the major arbitration institutions, including the ICC, Singapore International Arbitration Centre (SIAC), the London Centre for International Arbitration (LCIA), the London Maritime Arbitrators Association (LMAA), the United Nations Commission on International Trade Law (UNCITRAL) and the International Centre for the Settlement of Investment Disputes (ICSID).

He has long been recognised in the directories as a leading barrister for international arbitration. He is equally comfortable acting as part of a counsel team or as sole / lead advocate.

Mark also accepts appointments as arbitrator, having recently sat as sole arbitrator under the rules of the International Chamber of Commerce (ICC).

Highlights of Mark’s recent arbitration experience include:

• Oil and gas dispute between three oil majors (ICC Rules) – Mark acts for one of the oil majors in this dispute concerning the scope of a right of first refusal in a joint operating agreement related to one of the most valuable oil and gas deposits in the world (led by Ali Malek KC).
• M&A dispute between energy companies in East Africa (LCIA Rules) – Mark acted for the purchaser of shares in an East African energy company in a US$60 million fraud / breach of warranties claim (led by Nick Craig KC, 3VB).
• Oil and gas dispute in the Middle East (Gulf) region (ICC Rules) – Mark was instructed as sole counsel to a large Gulf energy company in an UNCITRAL arbitration concerning the scheme by which oil was to be extracted from a large offshore gas field.
• Energy related dispute in East Africa (ICC Rules) – Mark was sole counsel to a Kenyan subsidiary of an energy major in an ICC arbitration arising out of a fuel supply agreement.
• Banking dispute in the Middle East (ICC Rules) – Mark acted for a large Middle Eastern bank in a commercial dispute against an international banking conglomerate. The dispute concerned complex allegations of negligence and fraud, as well as the construction of a contractual indemnity as a matter of Shari’ah law (led by Rupert Reed KC, Serle Court).
• Aviation dispute in South-East Asia (SIAC Rules) – Mark acted for the claimant in a large dispute related to the supply of services under a series of contracts in the aviation sector.
• Dispute between shareholders in a large African oil & gas company (LCIA Rules) – Mark acted for the respondents in a complex and high value shareholder dispute under the LCIA rules between international parties, arising out of a series of English law-governed loan agreements.
• Oil & gas major v marine fuel supplier (LMAA Rules) – Mark acted as sole counsel to the claimant in a LMAA arbitration arising from contracts for the supply of bunkers to two vessels in a port in the UAE.
• Oil & gas major v Middle Eastern government (UNCITRAL Rules) – Mark acted, as part of a counsel team, for the claimants in a multi-billion dollar claim against a Middle Eastern jurisdiction related to contractual rights to the exploitation of oil and gas resources.
• Canadian natural resources company v Middle Eastern government (UNCITRAL Rules) – Mark acted as sole counsel for a Canadian natural resources company, in a contractual arbitration (English law governed) under the ICSID Additional Facility arising from a joint venture with a public body in a Middle Eastern country.

Mark has experience of acting as counsel to public inquiries. He was instructed as junior counsel on a statutory inquiry in England and Wales (under the Inquiries Act 2005) for a number of years. He also has experience of advising on an international inquiry conducted according to UN rules. Current and recent highlights of Mark’s public inquiries work include:

• Acted as Junior Counsel to the Independent Inquiry into Child Sexual Abuse in England and Wales, with particular responsibility for the investigation into institutional failures in England and Wales associated with offending abroad (in relation to which Mark was the Lead Junior Counsel). The investigation issued its final report in early 2018. The inquiry has a statutory footing and is mandated to examine whether public bodies and other non-state institutions have taken seriously their duty of care to protect children from sexual abuse in England and Wales (instructed by FieldFisher LLP).
• Advised the Royal Court of the Kingdom of Bahrain on the establishment and operation of the Bahrain Independent Commission of Inquiry chaired by Professor Cherif Bassiouni. Mark was part of a legal team which included Tariq Baloch of 3 Verulam Buildings and Amal Clooney of Doughty Street Chambers. The Commission represented the first time any sovereign state has willingly established a national commission composed entirely of international commissioners.