Sotiris is a dynamic advocate and one of the leading commercial arbitration specialists in Greece. He has handled numerous significant arbitrations under ICC, LCIA, SCC, Swiss, CAM, UNICITRAL and domestic rules across a variety of sectors and markets. He is one of Lambadarios’s expert counsels and an influential force at the very top of the firm.

Having specialised early in his career, Sotiris has rapidly established a reputation for insightful and expert counsel during high-value and commercially sensitive disputes and is one of the youngest-ever lawyers to be appointed by the ICC and parties as arbitrator. He sits as an arbitrator (presiding or sole arbitrator and co-arbitrator) in institutional and ad hoc international and domestic arbitrations. He also regularly acts as counsel in arbitration-related proceedings (including setting aside and recognition/enforcement). He has handled cases on a wide range of disputes across many sectors, including concessions within the construction industry, energy projects, shareholder disputes, and disputes relating to the hotel and leisure sectors as well as to the Greek defence sector. He has represented the European Commission as external legal counsel before the Courts of the European Union and has worked with the Legal Service of the European Commission.

Sotiris’s experience both as counsel in all forms of alternative dispute resolution and as arbitrator enhances the firm’s capabilities in structuring, managing and presenting dispute cases, and also in pre-litigation and pre-arbitration assessments. His practice at Lambadarios focuses on arbitration and commercial dispute resolution.

He holds a Ph.D. (summa cum laude) in international commercial arbitration from the Law School of the University of Athens; a Master of Laws (LL.M.) from the University of London – International School of Arbitration, Queen Mary; and a Law Degree from the Law School of the University of Athens.

Areas of expertise

Litigation - Dispute Resolution

Sotiris has significant experience in handling complex disputes in many sectors including engineering, energy (electricity and natural gas), construction, concessions, mining, commodities, anti-trust and state aid, privacy, and shareholders disputes, as well as disputes arising from main and offset agreements in the defence sector.

Notable Litigation - Dispute Resolution cases

  • ICC international arbitration between a leading US defense system corporation and the Greek State for the implementation of certain offset programs.
  • ICC international arbitration in the banking industry.
  • ICC international arbitration arising out of a major construction project in Greece.
  • ICC international arbitration over the licensing and supply of technology products.
  • LCIA international arbitration in the gaming industry.
  • UNCITRAL international arbitration arising out of a supply agreement.
  • SCC international arbitration arising out of a shareholders’ agreement.
  • Swiss Rules international arbitration in relation to a dispute arising out of the joint venture agreement and option agreement to purchase shares in the joint venture.
  • Ad hoc international arbitrations against the Greek State in relation to disputes over the construction of major national highways.
  • Ad hoc international arbitration arising out of a data processing agreement.
  • Ad hoc domestic arbitration between the Greek incumbent mining producer and the Greek incumbent power producer for the pricing of the supply of electricity.
  • Ad hoc domestic arbitration arising out of a hotel management agreement.
  • Proceedings before the Greek Courts for the recognition and enforcement of foreign arbitral awards issued in ICC arbitrations arising out of a major construction project in Doha, Qatar.
  • External legal counsel to the European Commission in cases T-392/08 and T-169/08 / T-421/09.
  • Sole arbitrator in ICC international arbitration subject to Swiss law in relation to a dispute arising out of a technology and trademark agreement.
  • Sole arbitrator in the first EODID arbitration arising out of a hotel leasing agreement.
  • Co-arbitrator in ad hoc domestic arbitration arising out of a shareholders’ agreement.
  • Advised Hellenic Public Properties (HPPC), the largest company for the management and development of private real estate assets of the Greek State, before the Greek Supreme Court in proceedings for the reversal of decisions by the Court of Appeal withholding certain arbitral awards for €700m.


Notable Arbitration cases

  • Advised OPAP S.A., the leading gaming company in Greece, in a London Court of International Arbitration (LCIA) arbitration against the Greek state.
  • Advised Engie Energy Services International, a French multinational utility company, for a €20m ad hoc arbitration proceeding arising out of a facility-management services agreement.
  • Lead advisors to Terna, a member of the GEK TERNA Group, and its joint-venture partner Renco in an ICC arbitration arising out of two construction sub-contracts with a value of €5m.

Notable Commercial Regulation cases

  • Advising on several major M&As, privatization and public procurement projects, particularly in the energy and construction sector (indicative clientele: Gazprom, SOCAR, Prysmian Group).
  • Advising Carlsberg Group and Olympic Brewery S.A. regarding the clearance of their merger from the Hellenic Competition Commission.
  • Advising Aegean Airlines for the clearance of its merger with Olympic Air from the European Commission.
  • Advising undertakings from the poultry and construction industry accused of participating in cartel arrangements.
  • Advising national and multinational corporations on compliance with EU and local data protection rules.
  • Acting as Data Protection Officer appointed by several entities in the energy, retail, wholesale and gaming industries.

Related News & Events

Lambadarios partner, Sotiris Dempegiotis, is a contributing author of the collective work “Arbitration – International | Domestic | Investment”


Who’s Who Legal: Lambadarios partner Sotiris Dempegiotis as a Future Leader


Lambadarios at the 4th Athens International Arbitration Forum


  • Advocate of the Greek Supreme Courts (2018)
  • Athens Bar Association (2008)
  • Member of the International Chamber of Commerce, Greece
  • Member of the International Arbitration Committee of ICC Greece (‘ICC Hellas’)
  • Member of the ICC Commission on Arbitration and ADR
  • Member of the ICC Task Force “Addressing Issues of Corruption in International Arbitration”
  • Advisory committee of the EODID
  • Greek
  • English
  • LLB University of Athens, 2005
  • LLM University of London, School of International Arbitration, 2007
  • PhD International Commercial Arbitration, University of Athens, Faculty of Law, 2015

Sotiris has published extensively on matters relating to arbitration law and is a regular speaker in arbitration-related seminars and conferences.

He is the author of International Commercial Arbitration and Competition Law, NOMIKI BIBLIOTHIKI, 2016 [in Greek] and has written numerous articles and commentaries including:

  • Comment on CJEU’s judgment in case C-284/2016 Slovak Republic v. Achmea BV, Business and Company Law, 2018, pp. 624-634 [in Greek].
  • Arbitration clauses and tort claims for breach of anti-trust rules, 118 Counsel (Sinigoros), 2016, pp. 30-32 [in Greek].
  • Arbitration as a dispute resolution mechanism in the energy sector, 25 Energy and Law, 2016, pp. 49-57 [in Greek].
  • EC competition law and international arbitration, Global Antitrust Review, 2008, pp. 135-148.
  • EC competition law and International Arbitration in the light of EC Regulation 1/2003, 25(3) Journal of International Arbitration, 2008, pp. 365-395.

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