Universiteit Leiden

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Kees Waaldijk

Professor of Comparative Sexual Orientation Law

Prof.mr. C. Waaldijk
+31 70 800 9593

Professor Kees Waaldijk has been a staff member of the Grotius Centre since 1 May 2011, when he was appointed to Leiden University’s new sponsored chair in Comparative Sexual Orientation Law, which is financed through the Betsy Brouwer Fund at the Leiden University Fund (LUF). Each Spring term he teaches the optional course Comparative Sexual Orientation Law, and every summer he runs the Summer School on Sexual Orientation and Gender Identity in International Law.

More information about Kees Waaldijk


Since May 2011 professor Kees Waaldijk is holder of Leiden University's chair in Comparative Sexual Orientation Law. This sponsored chair, financed through the Betsy Brouwer Fund at the Leiden University Fund (LUF), is part of Leiden Law School's Grotius Centre for International Legal Studies, at Leiden University's Campus in The Hague. His 2012 inaugural lecture, ‘The Right to Relate: A Lecture on the Importance of “Orientation” in Comparative Sexual Orientation Law’, was published in English, in Dutch, in Vietnamese and in Italian. In the Spring term of 2014 he also held the McDonald/Wright Chair of Law of the Williams Institute at the University of California in Los Angeles, teaching Comparative Sexual Orientation Law at UCLA School of Law.

Leiden University is unique by now having two chairs in the field of sexual and gender minorities, since in 2017 Jojanneke van der Toorn became professor by special appointment in LGBT Workplace Inclusion. Her chair (established at the initiative of Workplace Pride and financed by KPN) is part of Leiden University’s department of Social and Organisational Psychology.


Each Spring term Kees Waaldijk teaches the optional course Comparative Sexual Orientation Law, and every summer he runs the Summer School on Sexual Orientation and Gender Identity in International Law. Both attract participants from all over the world. He also gives guest lectures in various other courses, for example in Leiden Law School’s Advanced LLM in European and International Human Rights Law.

He also supervises master and PhD theses (and is convinced that the ideal format for a PhD thesis in comparative/international sexual orientation law is that of a series of articles).

In February 2018 his first PhD candidate, Jingshu Zhu, successfully defended her PhD thesis Straightjacket: Same-Sex Orientation under Chinese Family Law – Marriage, Parenthood, Eldercare.

Education and earlier career

In 1982 Kees Waaldijk obtained his Master Degree in Law (cum laude) at the Erasmus University of Rotterdam. He got his Doctoral Degree in 1994, at the University of Maastricht, with the thesis Motiveringsplichten van de wetgever (The Legislature's Duties to Give Reasons, in Dutch with summaries in English and French).

In 1982 Kees Waaldijk joined the then brand new law school of the University of Maastricht, where until 1995 he taught Public Law and Legal Skills. From 1987 until 1998 he was also part-time working for the University of Utrecht, The Netherlands, first as researcher and lecturer in the Department of Gay and Lesbian Studies, later as researcher at the Netherlands Institute of Human Rights (SIM). He was a guest lecturer for Sexual Orientation Law, Family Law and Legislative Drafting at various universities. In 1989 he spent a year in the United Kingdom, first as a senior visiting research fellow at the University of Edinburgh (Leverhulme grant), and then teaching British Constitutional Law at the University of Lancaster (ERASMUS staff exchange).

Since 1996 Dr Kees Waaldijk LLM works for Leiden University, until 2000 as a lecturer in jurisprudence , and from 1999 to 2001 as coordinator of the evening programme in law at the university's campus in The Hague. In Spring 2000, as visiting professor at Hastings College of the Law, University of California in San Francisco, he taught the course 'Human Rights Law in Europe - as applied to family, immigration and sexual orientation' (Leiden-Hastings exchange programme).  From  2000 until 2011, as Head of PhD Studies, he was responsible for the PhD programme of Leiden Law School, advising the PhD candidates, and teaching them about research methodology in law.

Research and social impact

Kees Waaldijk introduced the notions of ‘standard sequences’ and ‘small change’ to characterize the process of legal recognition of same-sex orientation in different countries. He has developed a Global Index on Legal Recognition of Homosexual Orientation (GILRHO), covering (de)criminalisation, anti-discrimination and partnership recognition in all independent countries of the world for all years since the 1960s. First results of this work in progress were published in the 2014 report The Relationship between LGBT Inclusion and Economic Development: An Analysis of Emerging Economies, which he co-authored with Lee Badgett and others.

Since publishing his first article on the opening up of marriage in 1987, Kees Waaldijk has contributed to the opening up of family law to gay and lesbian couples in the Netherlands and beyond. In 2017, in cooperation with Marie Digoix and others at the French National Institute for Demography INED, he completed the creation of the LawsAndFamilies Database – Aspects of legal family formats for same-sex and different-sex couples (www.LawsAndFamilies.eu), which covers 50 years of rights and responsibilities available – or not – through marriage, partnership or cohabitation in 21 countries. This large EU-funded project combines a detailed survey among 45 legal experts, with sociological interviews and statistical data. A first article was published in 2014 under the title ‘Great diversity and some equality: non-marital legal family formats for same-sex couples in Europe’, while the final report came out in 2017 under the title More and more together: Legal family formats for same-sex and different-sex couples in European countries – Comparative analysis of data in the LawsAndFamilies Database.

In his third line of research, Kees Waaldijk is looking how international legal standards concerning sexual orientation have been or could be emerging in different sub-areas of international law; see for example his article ‘Same-Sex Partnership, International Protection’ in the Max Planck Encyclopedia of Public International Law (updated version 2013).

He is co-author of a number of books, including:

For all his publications since 1996, see the tab ‘Publications’ above. For his publications since 1981 (and up to 2010), see:

Kees Waaldijk has been acting as a formal and informal adviser on issues of law & homosexuality to many (governmental, non-governmental, international) organisations. These include government departments, COC Nederland, the EU’s Fundamental Rights Agency, the UN Development Program, the International Lesbian, Gay, Bisexual, Trans and Intersex Association (about its annual report State-Sponsored Homophobia, a world survey of laws: criminalisation, protection and recognition of same-sex love), and Leiden University Pride. He also had an active role in several test cases and legislative lobbies, spreading news and information about sexual orientation law as it unfolded. He has given trainings to activists and politicians from different countries.

He was a member of the Dutch Government's Commission of legal experts advising on the opening up of civil marriage to same-sex couples (1996-1997), and a member of the Dutch Council for Family Affairs (1994-1999). From 1999 to 2007 he was one of the editors of the annual collection of opinions of the Dutch Equal Treatment Commission. He has been advising on evaluation studies commissioned by the Dutch government about the workings of the General Equal Treatment Act (1999), of the Law on Registered Partnership (1999 and 2006) and of the Law on the Opening Up of Marriage (2006).

From 2002 to 2004 he coordinated the European Group of Experts on Combating Sexual Orientation Discrimination, which reported to the Commission of the European Communities, about the implementation of the Employment Equality Directive. In 2006 this led to publication of the book Sexual Orientation Discrimination in the European Union by Kees Waaldijk and Matteo Bonini-Baraldi. 

Kees Waaldijk is a founding member of the European Commission on Sexual Orientation Law.

Professor of Comparative Sexual Orientation Law

  • Faculteit Rechtsgeleerdheid
  • Instituut voor Publiekrecht
  • Grotius Centre for Intern Legal Studies

Work address

Turfmarkt 99
2511 DP The Hague
Room number 4.45




  • European Commission on Sexual Orientation Law (ECSOL - www.sexualorientationlaw.eu) Member for the Netherlands (until November 2023 also Member of the Admission Committee)
  • Leiden University - Faculty of Social Sciences Member of Curatorium of the chair in LGBT Workplace Inclusion (held by Prof. J.M. van der Toorn)
  • International Lesbian, Gay, Bisexual, Trans & Intersex Association (www.ilga.org) Adviser for annual report State-Sponsored Homophobia - A world survey of sexual orientation laws
  • Various non-governmental, governmental and international organisations Occasional ad hoc adviser on issues of sexual orientation law
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