Prof. Dr. Nathalie Voser
LL.M. (Columbia)
Partner // Attorney-at-Law
nathalie.voser@rothorn.legal
t +41 44 212 11 22
m +41 79 222 28 41
Nathalie is a founding partner of rothorn legal. She has acted as counsel and arbitrator in a vast number of arbitrations under many major institutional rules. She has also advised and represented clients in arbitration-related state court matters (such as setting-aside proceedings before the Swiss Supreme Court) and in complex multi-jurisdictional disputes before Swiss and foreign state courts. Nathalie is a Swiss-trained lawyer but, as counsel and arbitrator, she has dealt with a wide range of other applicable laws, such as French, German, Japanese, Danish, English, Singaporean, Dutch, Austrian, Georgian, Jordanian, Romanian, Chilean, Turkish and Israeli law. Nathalie is fluent in German, English, French and Italian.
Nathalie is well known for her expertise in engineering and construction, renewable and non-renewable energy — particularly oil and gas-related projects (upstream, midstream, and downstream) — as well as the pharmaceutical, automotive, and technology industries. She has extensive experience in disputes arising out of research and development, distribution and licensing agreements, joint ventures, as well as (post)mergers and acquisitions. She is regularly appointed as arbitrator in both commercial and investment treaty arbitrations, including as the chair.
Chambers Global 2025 ranks Nathalie in Band 2 (Most In-Demand Arbitrators (Europe-wide), Arbitrators (Switzerland) & Arbitration Counsel (Switzerland)), describing her as a “brilliant legal mind” who is “always very practical,” adding that “she is one of the rare truly international arbitrators who runs a case smoothly and efficiently regardless of the seat and industry.” Chambers Global 2024 states that, “as an arbitrator,” Nathalie is “phenomenal” and that she is “very smart, practical and efficient.” According to Chambers Global 2023, Nathalie has “enormous knowledge and experience and is a delight to work with.”
Lexology Index 2025 ranks her as a “Global Elite Thought Leader” in Arbitration as well as a “Thought Leader” in Construction (2024) and writes that Nathalie is “a hugely impressive arbitrator” and “an obvious choice for complex and technical disputes,” that Nathalie is “strategic, efficient and thorough,” and that “the ‘fabulous’ Nathalie Voser is a market-leading name in the arbitration field who works across a range of industries, including engineering, construction and pharmaceuticals” (2023).
Nathalie is actively involved in the work of arbitral institutions. Nathalie is currently a member of the Advisory Board of the Japanese Commercial Arbitration Association (JCAA). She serves as Vice-Chair of the ICC Commission on Arbitration and ADR, and is a member of the ICC Arbitration Commission for the Swiss ICC National Committee. In the past, she acted as Vice President of the London Court of International Arbitration (LCIA), President of the European User’s Council of the LCIA, Board Member of the Swiss Arbitration Association, Board Member of the Vienna International Arbitration Chamber (VIAC), and Board Member of the Swedish Arbitration Institute (SCC). Nathalie has played a major role in various arbitration-related projects such as the 2004 IBA Conflict of Interest Guidelines, the 2012 ICC Arbitration Rules revision, and the 2017 SCC Rules revision. Until early 2022, she co-chaired the Taskforce of the IBA Arbitration Committee entrusted with the revision of the 2020 IBA Rules on the Taking of Evidence.
Finally, Nathalie is the author of several arbitration-related articles and of a leading arbitration textbook, the 5th edition of which was published in February 2024.
Experience (Excerpt)
Nathalie has recently acted or is currently acting in the following cases as counsel or arbitrator:
- Representing an operator of conventional and nuclear power plants in an ICC arbitration against an equipment company on claims arising from the design and delivery of equipment. The arbitration is governed by Swiss law and the seat is Geneva, Switzerland.
- Representing the operator of a renewable energy power plant in an ICC arbitration on claims arising out of an operation and maintenance agreement regarding the remuneration for services. The arbitration is governed by Israeli law and the seat is Tel Aviv, Israel.
- Presiding arbitrator in ICC arbitration regarding a complex, multi-party joint venture dispute regarding an airport infrastructure project. The arbitration is governed by Italian and Chilean law and the seat is Geneva, Switzerland.
- Presiding arbitrator in an ad hoc arbitration involving a dispute over claims arising out of multiple contracts concerning gas field operations in Africa. The arbitration is governed by the law of England and Wales as well as the law of the State of Texas and the seat is London, England.
- Presiding arbitrator in an ICC arbitration involving a dispute arising out of a “Tunnel, Dredging and Reclamation Contract” in relation to a claim for an adjustment of the contract price. The arbitration is governed Danish law and the seat is Copenhagen, Denmark.
- Presiding Arbitrator in a LCIA arbitration involving a dispute arising out of four sales agreements for copper products and the outstanding purchase price. The arbitration is governed by the Law of England and Wales and the seat is London, England.
- Co-arbitrator in a Swiss Rules arbitration involving a dispute concerning a long-term sponsorship agreement to sell beverages at defined sport events. The arbitration is governed by Swiss law and the seat is London, England.
- Co-arbitrator in an ICC arbitration involving a dispute concerning a Purchase Agreement and a supplier’s refusal to supply system-on-a-chip products. The arbitration is governed by Swiss law and the seat is Zurich, Switzerland.
- Co-arbitrator in a SIAC arbitration involving a dispute concerning Patent licensing agreements relating to rare-earth magnets. The arbitration is governed by Singaporean Law and the seat is Singapore, Republic of Singapore.
- Co-arbitrator in a SIAC arbitration involving a construction dispute concerning delay and disruption and extensions of time for the construction of a offshore windfarm. The arbitration is governed by Singaporean Law and the seat is Singapore, Republic of Singapore.
Qualifications
Nathalie graduated summa cum laude from the University of Basel and was admitted to the bar in Switzerland in 1990. She became a juris doctor with summa cum laude in 1992 and obtained an LL.M. with honors from Columbia University (New York) in 1994. In 2005, she received the venia docendi for private law, conflict of laws and comparative law, and in 2014, she was awarded the title of Professor of Private Law, Arbitration Law, Private International Law and Comparative Law by the University of Basel, where she regularly teaches courses in commercial arbitration and Swiss contract law.
Publications (Excerpt)
- International Arbitration – Comparative and Swiss Perspectives, 5th ed., Zurich: Schulthess, Baden-Baden: Nomos, 2024 (co-authored with Daniel Girsberger)
- Switzerland – in Christoph Liebscher (ed), The Healthy Award in International Commercial Arbitration, 2nd ed., Kluwer Law International, 2023, (co-authored with Sanela Ninković-Jakob, web version only)
- The 2020 Revisions to the IBA Rules of Evidence, ibanet.org (International Bar Association), 2023, (co-authored with Joseph E. Neuhaus, web version only)
- The Consequences of Achmea on Arbitrations Seated in Switzerland, in: The future of Investment Treaty Arbitration in the EU: Intra-EU BITs, the Energy Charter Treaty, and the Multilateral Investment Court, C. Baltag/A. Stanic (ed.), Wolter Kluwer 2020, pp. 115 – 142 (co-authored with Sebastiano Nessi)
- Besonderheiten einiger wichtiger Jurisdiktionen – Schweiz, in: Salger/Trittmann, Internationalen Schiedsverfahren, Praxishandbuch, 2019
