Advokatfirmaet Thommessen AS‘s wide-ranging EU/EEA and competition practice encompasses antitrust, public procurement, and state aid regulation. As a result of its broad sector expertise spanning from telecoms to energy, the firm receives a varied stream of work. Siri Teigum is experienced in cases in the EFTA Court and CJEU, as well as in merger clearance matters. New practice head Eivind J Vesterkjaer’s expertise across all aspects of competition law bolsters the team’s offering, while Wenche Sædal chiefly focuses on EU/EEA law and state aid. In a team development, Svein Terje Tveit joined from Arntzen de Besche in December 2025. Former practice head Heidi Jorkjend left the firm in December 2025.

Legal 500 Editorial commentary

Accolades

Client satisfaction: Sector knowledge

Client satisfaction: NPS ®

Testimonials

Collated independently by Legal 500 research team.

‘Heidi Jorkjend has been indispensable in helping us assess competition law risk. She combines deep legal knowledge with a keen understanding of what is feasible and commercially sensible. Heidi is not only technically strong but also excellent at seeing issues from our side. Her advice is clear, practical, and timely.’
‘Thommessen’s practice is excellent. They provide strong guidance on risk assessment under competition law, are thorough with regulatory compliance, and understand how legal requirements interact with our business strategy. The team is proactive, precise, and responsive.’
‘Thommessen’s competition team is skilled and experienced, and manages to balance the ability to identify risks and find pragmatic solutions to address them.’
‘I recommend Eivind J Vesterkjaer.’
‘Knowledgeable, very responsive and understanding of the client's situation - highly solution oriented.’
‘Eivind J Vesterkjaer is, with his unique combination of commercial understanding, attention to detailed regulations, and the ability to create friendly and cooperative discussions with the clients, a dream to work with.’

Key clients

SpareBank 1 Kongsberg Gruppen Veidekke ASA Ringnes ASA Gyldendal ASA Lindum AS Halliburton Sandbrook Capital and Public Sector Pension Investment Board (PSP) Vestdavit AS Eviny AS BAMA NorgesGruppen ASA Circle K Mestergruppen El-Proffen AS Ferd Triton Partners DAF Trucks N.V. / DAF Trucks Deutschland GmbH Lyse AS / Lyse Produksjon AS Kahoot! ASA Storebrand ASA HitecVision Bomega AS Elkem ASA Altor Apotek 1 Gruppen BW LPG Limited Danske Bank Wintershall Dea BW Offshore Limited Bane NOR Fremtind Forsikring AS DOF ASA Norvestor One Equity Partners Gearbulk Holding Bain Capital Europe VI General Partners

Work highlights

Advising NorgesGruppen ASA in connection with the Norwegian Competition Authority's issuance of a NOK 5bn fine relating to an alleged 'by effect' infringement based on information exchange.

Advised Kongsberg Defence & Aerospace AS on the establishment of a joint venture with Thales within defence communications.

Advising DNB ASA on its acquisition of Carnegie Holding AB - a securities company with activities in Norway, Sweden and Denmark - and assisting with merger filing and clearance in Norway.

Lawyers

Hall of Fame

The lawyers at the very top of the profession, widely known and respected by peers and clients for their longstanding involvement in market-leading work.