Our Team
Clayton & Segura is the only international law firm dedicated exclusively to state aid in Europe.
Our Story
Founded by partners with two decades of state aid experience gained within regulators and leading law firms, Clayton & Segura delivers direct, partner-led advice supported by a dedicated team of skilled professionals.
With solid expertise in state aid and in-depth knowledge of decision-making processes within EU and EFTA institutions, the firm is uniquely positioned to guide clients.
Our extensive network of contacts within the European Commission and the EFTA Surveillance Authority, combined with our ability to provide advice in English, French, German, and Spanish, ensures tailored, strategic support.
This firsthand experience offers unmatched insight into the complexities of state aid, enabling us to serve law firms, undertakings, and public authorities with precision and confidence.
Our Team

Maria Segura
Partner
Member of the Madrid and Brussels (E-List) Bars
Notable Experience:
Freshfields Bruckhaus Deringer Berlin; European Commission, DG Competition; Former Deputy Director of the Competition and State Aid Directorate of the EFTA Surveillance Authority; Managing editor of the ‘European State Aid Law Quarterly (EstAL)’.
Education:
Universities of Zaragoza, Pau, Vienna and Europa-Institute Saarbrücken
Member of: FIDE and EVER Alumni

Marianne Clayton
Partner
Member of the Paris and Brussels (E-List) Bars
Notable Experience:
Freshfields Bruckhaus Deringer Paris; Bredin Prat Brussels; Senior Officer of the Competition and State Aid Directorate of the EFTA Surveillance Authority
Education:
Universities of King’s College London & Paris I – Sorbonne
Member of: FIDE and King’s College Alumni

Nadia von Bassewitz
Of Counsel
Rechtsanwältin, Member of the Bar Schleswig-Holstein (Germany)
Notable Experience:
Competition advocacy consultancy in Brussels; Competition law expert for trade associations in sub-Saharan Africa; State Aid Directorate of European Commission, DG Competition
Education:
LL.M. (College d’Europe), Maître en Droit (Université Paris X), University of Münster
Member of: College of Europe Alumni Association

Christopher M. Vollert
Associate
Rechtsanwalt, Member of the Munich Bar
Notable Experience:
GvW Graf von Westphalen, Munich/Hamburg; Stagiaire at the State Aid Directorate of the European Commission, DG Competition
Education:
Universities of Munich, Speyer, Brussels School of Competition

Sofia Medina Sanchez
Junior Associate
Notable Experience:
Stagiaire at the State Aid Directorate of European Commission, DG Competition
Education:
Autonomous University of Madrid, Universities of Maastricht, Leiden, and Open University of Catalunya