Governments and international organisations
Kingdom of the Netherlands: making part of the team of legal experts overseen by Judge Kapteyn dedicated to the legal analysis of the restructuring of the Dutch Overseas territories, I was responsible for the assessment of the application of EU law in the Caribbean parts of the Kingdom, informing a radical 2010 update of the constitutional structure of the Kingdom, splitting up the Netherlands Antilles into 5 entities enjoying different legal statuses in national constitutional law, but a single OCT status in EU law (10.10.10 regeling) [bijlage kamerstukken].
Republic of Malta: upon the request of the Attorney General, I was involved hands-on in the 2014 reform of Maltese citizenship law. As a member of the Maltese governmental delegation with Prime Minister Muscat's mandate I negotiated on behalf of Malta with the European Commission, to ensure the full endorsement by the European Commission of the new law. I equally provided legal advice on EU law to Identity Malta, one of the Government agencies.
European Parliament: I co-authored a major expert report on the EU Mechanism for Democracy, the Rule of Law and Human Rights, to inform the position of this institution in the context of the on-going Rule of Law debates in the EU triggered by the Rule of Law backsliding in Hungary and Poland [full text].
House of Lords (UK): I contribute written evidence to the expert reports of the EU Committee; Foreign and Commonwealth Office (UK) I contributed evidence to the 'Review of the Balance of Competences between the United Kingdom and the EU' in the field of EU Enlargement, focusing on the issues of the Rule of Law [HM Government Report].
I also shared expertise, inter alia, with the European Commission (DJ Justice, EU citizenship law); the European Economic and Social Committee (Working Group of the Future of Europe) and EU Overseas Countries and Territories Association (OCTA) (EU Law of the Overseas).

Law firms
Clifford Chance: I participated as EU law expert in the Bancoult No 3 case (Chagossians' navigation and fishing rights in the BIOT) first in front of the High Court and then in front of the Court of Appeal of England and Wales on mass deportations from the Chagos Archipelago on the request of Clifford Chance, representing the islanders against the Crown (2012–2014);
I was engaged as an expert also by Osler, Hoskin & Harcourt (Investment Protection Arbitration, issues of EU Constitutional Law); Everaert Advocaten (EU migration law); and designed the Quality of Nationality Index together with Henley & Partners. The index is now published by Bloomsbury in London as "Kälin and Kochenov's Quality of Nationality Index" and is co-edited with Justin Lindeboom.