Bertrand Mariaux Avocats is a boutique commercial law firm with a special expertise in social entrepreneurship law.

We have a strong pro bono practice. 

We also assist asylum seekers.

We believe in legal aid (assistance judiciaire). Legal aid is open in cases of modest or nonexistent income.



Bertrand Mariaux Avocats works with asset management structures, investment funds and enterprises (non-profit or commercial) having an intentional & positive impact on society as well as for the social & solidarity economy.




The firm is born from a dual passion for law and positive social impact. BMA works with a passionate team of five lawyers registered at the Luxembourg and Paris law societies (barreaux de Luxembourg et de Paris). The firm acquired experience from top tier international UK, American, Dutch and French law firms, and trained at prestigious law and business schools around the world.




Due to its experience and unique character, the firm provides a wide variety of legal services advising in investment funds, corporate & tax law as well as in dispute resolution and it advises in all aspects surrounding impact investing and social & solidarity economy law in Luxembourg and France.

Bertrand Mariaux Avocats advises in simple and complex commercial, financial structuring (company formations, mergers & acquisitions), social business (sustainable business, green business), corporations (corporate social responsibility - CSR), traditional and social banking (green finance, social finance, responsible finance, microfinance), investment funds (private equity funds, hedge funds), securitisation with a commercial or social purpose, and in social impact investment funds (environmental, social & governance - ESG, socially responsible investment - SRI, social venture capital).

The firm closely works with the social & solidarity economy sector (social enterprises, agrément sociétés d’impact sociétal - SIS, agrément entreprises solidaires d’utilité sociale - ESUS, cooperative companies, charities), philanthropy (foundations) and nonprofit organisations (associations sans but lucratif - ASBL, loi 1901).




The firm works with a variety of clients, both small and large, from established corporations, charities and social enterprises to innovative start-ups and high-profile individuals. Its clients are also national and international public or private institutions (NGOs, professional groups).


Bertrand Mariaux

Bertrand Mariaux.JPG

Bertrand Mariaux is a registered lawyer with the Luxembourg (Liste 1 - oath-taking, 2011) and Paris (oath-taking, 2010) law societies. He has an LL.M. (hons), is a Certified Expert in Microfinance and has studied social entrepreneurship and impact investing. Bertrand has been involved in social entrepreneurship and microfinance projects.



Before founding Bertrand Mariaux Avocats, Bertrand has gained skills and robust experience within top-tier international UK based "Magic Circle" law firms covering aspects including investment funds, mergers & acquisitions, corporate finance, capital markets, and regulatory matters. He also trained at a top-tier international French law firm in Paris.

In addition, Bertrand successfully managed all legal affairs within the Financial Risk Unit of the Risk Management Department at the European Investment Bank.

Recently, Bertrand gave a presentation before the Haut Conseil à la Vie Associative in Paris (a French Prime Minister office's institution dedicated to the non-for-profit sector) about the latest piece of Luxembourg legislation on Social Impact Company (Sociétés d'Impact Sociétal - SIS).

Among other social impact investing ventures, Bertrand has volunteered and worked on projects involved in scaling the microfinance operations of an NGO in Uganda.

He is also one of the founding members of the Institut Luxembourgeois de Médiation, a nonprofit alternative dispute resolution organisation.


Bertrand is a registered Lawyer in Luxembourg (2011) and France (2010). While studying at the bar School in Paris, he obtained an LL.M. with distinction from Bond University. 

Bertrand has also acquired experience, skills, and knowledge in impact investing, social entrepreneurship & business. He has studied with the University of Oxford and the Wharton School of the University of Pennsylvania and is a Certified Expert in International Microfinance from the Frankfurt School of Finance & Management.

While at the Paris Bar School Bertrand also founded a legal aid association in a disadvantaged Paris suburb which finally received the support of the Paris Law Society.


Internship Opportunity (stage conventionné)

Would you like to gain experience in a diverse and unique field, doing something that makes a real difference in a demanding, efficient, rewarding (we encourage initiative-taking and decision-making) yet flexible and human environment, with real autonomy (both teleworking and working on a part-time basis are possible)?

You enjoy and are comfortable working and learning in a highly innovative work environment using the latest technologies.

You are an autonomous, serious, punctual, persistent and patient. You are self-confident but capable of questioning your decisions and actions where appropriate. You are detail-oriented, not perfectionist, but always striving for excellence, and constantly looking to improve. You are resourceful. You like taking the initiative. You are continually looking for the best ways to improve yourself and help those around you. You identify strongly with Bertrand Mariaux Avocats’s core mission of bringing as much value as possible to the world in our field of expertise and beyond.

This is not compulsory, but you may email your CV and/or cover letter to

For greater efficiency, you may also contact us (or Bertrand individually) through any form of social medias instant messaging (see links at the bottom of this page). We may be very busy, so feel free to send several messages and ask us again about your application. Also please do not hesitate to apply again in the future, even if you did not initially receive a favourable response (or no response at all). This will demonstrate your determination and motivation to be willing to work with Bertrand Mariaux Avocats.

Your CV is not your most important asset! We prefer someone who either already has the qualities mentioned above or is seeking to acquire and maintain them.

We look forward to working with you.

Bertrand Mariaux,

Avocat aux barreaux de Luxembourg et de Paris


Bertrand Mariaux Avocats

22, avenue de la Liberté

L-1930 Luxembourg

Grand-Duchy of Luxembourg

☎︎ +352 27 40 39 40

📠 +352 27 40 39 41

Consultations on site or by telephone

By appointment only, except in case of emergency