About LexOceana
LexOceana is an independent legal consultancy based in The Hague, specialising in public international law, international dispute settlement, and ocean affairs.
The practice focuses on advising and representing States in contentious disputes, advisory proceedings, and complex sovereign claims, with particular expertise in the law of the sea, maritime zones, and ocean-related legal regimes. LexOceana operates as a boutique practice, offering highly specialised, senior-level advice tailored to the needs of governments and public institutions engaged in international litigation and multilateral processes.
Founder and Director
LexOceana was founded and is directed by Lesther Antonio Ortega Lemus, an international lawyer, public notary, and career diplomat with extensive experience in international adjudication, multilateral diplomacy, and strategic litigation management.
He has served as Co-Agent, Representative, Counsel, and Advocate in proceedings before the International Court of Justice, the International Tribunal for the Law of the Sea, and arbitral tribunals constituted under the auspices of the Permanent Court of Arbitration, in both contentious and advisory contexts. His work has included cases involving sovereignty, territorial and maritime delimitation, navigation, climate-related advisory proceedings, and other matters of public international law.
International Litigation and Advisory Practice
The practice combines legal advocacy with strategic coordination of international litigation, including the formulation of litigation and procedural strategies; the organisation and management of international legal teams; the selection and coordination of counsel, advisers, and technical experts; the handling of diplomatic and image-related aspects of sensitive disputes; and the effective use of historical, cartographic, and technical evidence.
Ocean Affairs and the Law of the Sea
A core area of specialisation is the law of the sea, including the interpretation and application of UNCLOS, maritime jurisdiction, navigational regimes, marine environmental protection, and ocean-related dispute settlement mechanisms.
Diplomatic and Multilateral Experience
In parallel with legal practice, Mr Ortega Lemus has served as a career diplomat with the rank of Minister Counsellor, including postings in The Hague and London, and functions as Chargé d’Affaires and Deputy Head of Mission. His diplomatic experience includes representation before, and engagement with, a wide range of international organisations and bodies, including the OPCW, PCA, ICC, IMO, and other multilateral institutions.
Approach
LexOceana is intentionally structured as a small, independent consultancy, allowing for direct senior involvement, discretion, and adaptability. The practice does not seek volume work, but rather selective engagement in matters requiring expertise, judgment, and trust.
The firm’s work is conducted from The Hague, at the centre of international adjudication. Its size and flexibility enable it to quickly adapt and deliver bespoke services tailored to each client's specific needs.