Advokatfirmaet Thommessen AS

About the Firm

Thommessen is a Norwegian law firm headquartered in Oslo with additional offices in Bergen, Stavanger and London. The firm’s clientele comprises both national and international businesses across the public and private sectors.

Thommessen boasts a diverse portfolio of legal expertise, currently boasting a dedicated team of 288 lawyers. The firm prioritises a client-centric approach, understanding that businesses require tailored solutions, and it strives to go above and beyond to provide legal advice that fosters long-term value creation.

Established in 1856, Thommessen is considered to be one of Norway’s leading commercial law firms. The firm provides advice to Norwegian and international companies, as well as organisations in the public and private sectors, ranging from small and medium-sized enterprises to large multinational corporations. Thommessen covers all business-related fields of law.

The firm's strong reputation is built upon a foundation of integrity, quality and innovation. As Thommessen looks ahead,it embraces new technologies and approaches to enhance its services, ensuring that it remains at the forefront of the legal industry. The firm’s digital products and services under ThommessenFlow are designed to simplify processes, enhance knowledge sharing, automate documents and provide a secure client portal.

The firm is a member of LexMundi, a global network of independent law firms.

Thommessen has garnered an array of awards and accolades, including its recognition as Norwegian Law Firm of the Year at Chambers and Partners Europe Awards 2021, Mergermarket’s ranking of the firm as Norway M&A Legal Advisor of the Year for three consecutive years and Norway Firm of the Year by Who’s Who Legal.

Managing Partner: Sverre Tyrhaug

People Count: 320 partners and associates

Practice Areas

The firm provides comprehensive legal counsel encompassing venture capital and growth equity, the Norwegian Security Act, technology and digitalisation, tax and duties, sustainability and climate risk, shipping and offshore, export control and sanctions, renewable energy and infrastructure, real estate, public procurement, proptech, private equity, oil service, oil and gas, maritime and offshore emergency response, M&A and corporate law, life sciences and health tech, intellectual property and marketing law, insurance, restructuring and insolvency, fishery and aquaculture, fintech, finance regulation, EU/EEA and competition law, equity capital markets, employment, dispute resolution, defence and security, debt capital markets, data protection and cyber security, crisis management, consumer markets, construction and contract law, compliance, banking and financing, asset management, and criminal liability and administrative sanctions.

Thommessen’s industry expertise covers banking and finance, renewable energy, technology, shipping and offshore, oil and gas, oil service, aquaculture and fisheries, defence and security, and real estate.

EU/EEA and Competition Law Practice:

Thommessen is recognised as a leading firm in Norway for its expertise in EU/EEA and competition law. The firm provides comprehensive assistance to both Norwegian and international companies in merger control processes, appeals, investigations and litigation proceedings. Additionally, Thommessen offers ongoing legal advice on State aid law, competition law and other aspects of EEA law.

Since the signing of the EEA Agreement in 1992, Thommessen’s lawyers have played a key role in the evolution of EU/EEA law and Norwegian competition law. The firm has been involved in drafting key legislation and has represented both Norwegian and international clients in numerous significant and landmark cases. This includes acting as counsel before Norwegian courts, the EFTA Court, the Competition Appeals Board and the European Court of Justice.

Thommessen has been at the forefront of most major cases in this area of law in Norway, handling complex mergers and addressing potential competition law violations. Many of these cases have not only shaped legal precedent but have also been of considerable financial and commercial importance to the firm's clients.

Building on this extensive experience, Thommessen supports clients in contract negotiations, transactions, commercial projects, dispute resolution and major investigations across various industries. The firm strives to be a solution oriented, constructive and accessible partner in all its engagements.

Debt Financing and Financial Regulation Practice:

Thommessen has a dedicated specialist group with extensive experience in debt financing and financial regulation. Its lawyers provide ongoing, practical advice to a wide range of companies in the financial industry and are regularly involved in large transactions. The firm distinguishes itself through its in-depth knowledge of both Norwegian and European regulatory processes, combined with practical insight into the actions of regulatory authorities in different situations.

Thommessen closely monitors regulatory developments in the financial services sector and frequently advises clients on lobbying efforts and interactions with governmental agencies in Norway and the EU.

History

1856:

In 1856, Hans Christian Harboe Grønn established a private law practice in Oslo. He was dedicated to promoting the independence of the legal profession from the civil service and to advancing the internationalisation of commercial law. During a period of significant economic growth, his practice quickly prospered. Grønn eventually retired early to pursue his passion for sailing and designing racing boats. Although his name was removed from the firm's name in 1890, his values and vision laid the groundwork for a legal practice that would later play a central role in many of the key developments in Norwegian business.

1907:

By 1907, large-scale hydropower development was transforming Norway’s industrial landscape. That year, attorney Per Rygh was appointed to manage two companies he had helped establish: Norsk Kraftaksjeselskap and A/S De Norske Salpeterverker. He worked in close collaboration with the industrial entrepreneur Sam Eyde on ventures that would later become the foundation of major Norwegian companies such as Norsk Hydro and Elkem. These enterprises were instrumental in the expansion of Norway’s hydropower sector. Alongside Carl Lundh, Per Rygh emerged as one of the country’s leading legal advisors in hydropower and industrial development.

1928:

In 1928, attorney Gunnar Greve founded a law firm in Bergen that would, over time, become the largest legal practice in Norway outside Oslo – Greve, Greve, Greve & Lorentzen. Gunnar Greve Sr. earned a reputation as the leading legal advisor in Western Norway, known for his deep involvement in both the region’s business community and its cultural institutions. His dedication to his clients and work was unwavering, as he himself remarked: "If you believe in the importance of rest and relaxation, this firm is probably not the place for you."

In 1954, Herm Otto Krefting established his own law firm in Oslo, later joined by Håkon Løchen as partner. At a time when Norway was undergoing major tax reforms, the firm quickly assumed a prominent role in the field of tax law. Krefting was also a proponent of modernising law firm operations and was actively engaged in trade and industry developments.

1959:

By 1959, Norway had secured control over parts of the North Sea located south of the 62nd parallel, setting the stage for the country’s petroleum era. Exploratory drilling began in the mid-1960s and was initially led by international companies, which were also responsible for the development of the first oil and gas fields. In 1963, the Norwegian government formally declared that all natural resources beneath the seabed on the Norwegian continental shelf belonged to the state. This decision laid the legal and economic groundwork for what would become a major source of national wealth. In the years that followed, lawyers from the firm played an important role in supporting the structural developments and major transactions taking place on the continental shelf.

1990:

The 1990s marked a period of significant growth and consolidation in the Norwegian legal sector, and Thommessen played a central role in these developments. In 1990, the firm Thommessen & Krefting was founded in Oslo. The following year, it merged with the Greve firm based in Bergen, resulting in the formation of Thommessen, Krefting & Greve. In 1993, three partners from the shipping-focused law firm Lund & Co. joined the practice, prompting a further name change to Thommessen Krefting Greve Lund.

2009:

By 2009, the lengthy firm name was deemed impractical, and it was simplified to Thommessen. The decision was made for the sake of clarity and simplicity, despite the fact that none of the firm's partners at the time bore the Thommessen name, while Krefting, Greve and Lund were still represented.

2025 – The Way Forward:

As of 2025, Thommessen continues to advise many of Norway’s leading businesses and remains closely engaged with the internationalisation of commerce, the evolving legal and regulatory framework for technology, and the challenges and opportunities presented by the green transition. The firm now has more than 400 employees, including approximately 300 attorneys and associates, delivering high-end legal services to both private and public sector clients in Norway and abroad.

In August 2021, Thommessen’s Oslo office relocated to new, modern premises in VIA Vika. A similar move took place in June 2024, when the Stavanger office moved into the K8 building in the city centre. The Bergen office is also set to relocate in 2027. These relocations support the firm’s vision for the law firm of the future – one built around improved information flow, collaboration, knowledge sharing, and innovation.

Culture & Values

Thommessen is actively seeking to create a firm characterised by greater diversity. The organisation is committed to providing equal opportunities for all employees and encourages individuals to be their authentic selves in the workplace, regardless of background, gender, religion, ethnicity or sexual orientation. The goal is to ensure that everyone, including new employees, feels welcomed and empowered to contribute fully.

For many years, Thommessen has taken a structured approach to achieving gender balance across all levels of the firm – a milestone it has now reached. In recent years, it has also increased the proportion of female partners and remains committed to further progress in this area. To support its diversity and inclusion objectives, the firm has implemented a number of targeted measures, including inclusive recruitment strategies, support for employees with young children, and leadership development programmes.

The firm’s dedicated Diversity and Inclusion Committee plays a central role in fostering a culture of equality and respect at Thommessen. The committee works to maintain an inclusive working environment where all individuals feel acknowledged, valued, and respected. Comprising engaged employees who are passionate about supporting the firm’s culture, the committee partners closely with management to help achieve the firm's diversity, inclusion, and equality goals.

The committee is also responsible for organising internal initiatives and campaigns that promote awareness and inclusion. Throughout the year, Thommessen hosts events and activities aligned with key dates such as International Women’s Day, Pride, and World Mental Health Day.

Values

Reliable:
Thommessen is reliable, because it has an unwavering commitment to integrity and quality that stands the test of time. The firm is accessible and delivers on its promises to clients and colleagues. It looks after its people and provides a safe and inclusive workplace for all.

Curious:
Thommessen is curious, because it wants to learn from, and understand, its clients and their challenges. The firm asks relevant questions, and it listens. Thommessen is curious about market trends, new technologies, digital transformation, economics, politics, sustainability and society.

Team Player
Thommessen is a team player, because it is motivated by the pursuit of shared objectives and convinced that working as one team is the key to providing businesses with industry-leading legal services. The firm stands by its people in challenging situations and celebrates as one team when it succeeds.

Corporate Responsibilities

Thommessen seeks, together with its clients, to shape the business sector of the future and to safeguard corporate values and the rule of law. The firm’s social involvement is reflected not only in the work it does, but also through the NGOs it supports. Thommessen supports several ambitious CSR and pro bono initiatives. Knowledge is the firm’s key resource and represents its main contribution to enabling NGOs to pursue their mission under optimum conditions.

Thommessen’s main CSR partners:

Doctors Without Borders

Oslo Pride

=Kaffe

Big Enough Global

Sustainability:
Well-functioning businesses are sustainable businesses. As advisors to both Norwegian and international businesses, Thommessen aims to guide them towards future-oriented and sustainable solutions.

Sustainability intersects with all industries and aspects of business. Sustainable development is a key priority for the firm, irrespective of whether the speciality is tax, renewable energy, financing, public procurement, shipping or another field. Therefore, the firm took an early lead in establishing an interdisciplinary sustainability group with a specific sustainability and climate risk remit. This group consists of partners, attorneys and associates from various disciplines.

In addition to working with its clients to advance their sustainable development agendas, Thommessen has an internal green committee, ThommessenZero, which actively seeks to reduce the firm’s greenhouse gas emissions and other environmental impacts.

Key Clients