Marlen Estévez leaves RocaJunyent and founds Marest Law, an AI-native business law firm in Madrid

Marlen Estévez Sanz, until a few weeks ago a partner and head of the Litigation, Arbitration and Mediation department at RocaJunyent in Madrid, has launched her own firm. It is called Marest Law, it is based in the capital's Justicia district and it describes itself as a business law firm. The announcement was made on 19 October 2026.

This piece collects what the firm itself and the specialist press have published. Where information comes from the firm, we say so.

What has been announced

According to Iberian Lawyer, Estévez said on LinkedIn that she left RocaJunyent on 30 September, after almost nine years at the firm. The same publication had reported on 23 September that she was preparing an independent project.

Marest Law starts with five practice areas:

• Dispute resolution.
• M&A and corporate law.
• Restructuring and insolvency.
• Labour.
• Tax.

The firm says it will advise companies, executives and investors, both in Spain and on matters with an international element. For those cases it will rely on a network of law firms and specialists in other jurisdictions.

A model built on senior partners and technology

The firm sums up its way of working with the motto "Building Bridges": connecting the law with business strategy, and also different specialisms and jurisdictions. Teams are put together for each matter and, according to the firm, with the direct involvement of partners.

Another feature it stresses is that it is "AI-native". Its explanation is that technology is part of its method from day one, to cut lower-value tasks and leave lawyers more time for legal judgement, strategy and client contact. It has not said which tools it uses, so this is best read as a statement of intent. It is worth remembering that using AI in legal practice requires human checking, as we explain in our review of sanctions for AI-invented case law.

Who the founder is

Estévez has built her career around litigation, arbitration and mediation. The sources mention matters arising from corporate transactions, directors' liability and shareholder disputes, as well as advice to boards of directors on corporate governance.

Outside the firm, she chairs the Madrid Business Mediation Centre (CMEM) and CIIAM Mediación, and she is the founder and president of Women in a Legal World. The launch materials also link her with the Royal Academy of Jurisprudence and Legislation, the International Bar Association and the International Chamber of Commerce.

The advisory board, still without names

The firm announces an academic and business advisory board. It is still being assembled and its members will be made public later. According to the firm, it will not give legal advice, which will remain solely with Marest Law's lawyers. It will act as a forum for testing ideas on matters with economic or reputational impact, and it will cover corporate governance, AI governance and dispute resolution methods.

What we still do not know

The published material does not, as of today, give the number of lawyers or the names of any other partners. There is also no information on clients. Until the firm provides it, we do not treat any of it as fact.

Why it matters for the market

When a partner who sits on a firm's governing body leaves to found her own, the move matters beyond the names. Departures like this tend to raise practical questions: what happens to ongoing matters, and which notice periods and agreements apply. The general rules are in our guide to lawyers' lateral moves, notice and non-competition. If the new project takes a corporate form, the usual framework is the Professional Companies Act. We do not know which legal structure Marest Law has chosen, and we do not infer it.

We will keep following firm news in our big law firms and lateral moves section. If you work at a firm and want to announce a hire or a launch, you can send us the release through the site form.

A note on the image

The photograph of Marlen Estévez comes from the press release distributed by the firm and published by Lawyerpress. The photographer's name is not given. If the firm or the author prefer a different credit or want it removed, we will correct it straight away.