LAWYER PROFILE
Jeffrey Sullivan KC

Jeffrey Sullivan KC

UK 2026

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Ranked in 3 practice areas

About

Provided by Debevoise & Plimpton LLP

Practice Areas

London partner Jeff Sullivan KC is a member of the International Dispute Resolution Group and Co-Chair of International Arbitration in Europe. Mr. Sullivan’s practice focusses on international arbitration and public international law.

Mr. Sullivan is one of the market’s leading and most respected advocates, representing clients in commercial and investor-state arbitrations before all the major arbitral institutions. He also regularly sits as an arbitrator, and advises clients in all aspects of public international law.

Mr. Sullivan has advised clients from a range of sectors and regions, but has a particularly deep practice focussed on disputes in the energy, extractive industries and infrastructure sectors.

His experience includes disputes involving long-term supply agreements, concession agreements, production sharing and operating agreements, joint venture agreements, EPC and other construction agreements.

Mr. Sullivan has also acted as counsel and lead advocate in more than 30 bilateral investment treaty and Energy Charter Treaty arbitrations, and has advised nation states in Europe, Central Asia and the Middle East on the negotiation and drafting of trade and investment treaties.

Recent experience includes a $4 billion ICC arbitration centred on a Middle Eastern infrastructure project; an UNCITRAL arbitration concerning a $750 million transport project dispute; acting for 25 investors in renewable energy projects in 10 separate ICSID and UNCITRAL arbitration claims against the Kingdom of Spain under the Energy Charter Treaty involving claims in excess of $2.5 billion; and two parallel LCIA arbitrations with the amount in dispute in excess of $2.2 billion.

Chambers Review

Provided by Chambers

Chambers Guide to the Legal Profession

International Arbitration - UK-wide

Band 1
Band 1

Individual Editorial
Jeffrey Sullivan KC is co-chair of Debevoise's arbitration group in Europe. He is particularly known for his expert handling of claims brought under the ECT, which forms part of his extensive investor-state arbitration practice. He demonstrates strength across the energy and infrastructure sectors.

Energy & Natural Resources: Disputes - UK-wide

Band 2
Band 2

Individual Editorial

Jeffrey Sullivan KC of Debevoise & Plimpston is a respected energy disputes lawyer with strong experience of handling claims in both the oil and gas and renewables sectors. He is highly adept at assisting with Energy Charter Treaty claims and the annulment of intra-EU investment treaties.

Public International Law - UK-wide

Band 3
Band 3

Individual Editorial
Jeffrey Sullivan KC has a strong profile in the international arbitration field, regularly acting for investors in ICSID proceedings and disputes under the ECT. His practice also focuses on the intersection between EU law and investment treaty rights.

Strengths

Provided by Chambers

  • Jefferey is extremely clear and sees any issues straight away.

    International ArbitrationChambers Guide to the Legal Profession
  • Jeffrey has an excellent technical skill set.

    International ArbitrationChambers Guide to the Legal Profession
  • Jeff is always available, delivers straightforward practical advice and is great at handling clients.

    International ArbitrationChambers Guide to the Legal Profession
  • Jeffrey is an excellent operator with extensive experience, sensible judgement and measured advice.

    International ArbitrationChambers Guide to the Legal Profession
  • Jeffrey provides excellent support.

    International ArbitrationChambers Guide to the Legal Profession
  • Jeffrey is super impressive and a great guy.

    Energy & Natural Resources: DisputesChambers Guide to the Legal Profession

Ranked Individuals at Debevoise & Plimpton LLP (32)

London (Firms)

UK-wide

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