Constantinus Albertus Josephus Maria "Constantijn" Kortmann (14 March 1944 – 24 January 2016) was a Dutch professor of constitutional law.
In 1964, he studied the French language for half a year at the Institut Catholique in Paris, France.
The handbook Constitutioneel Recht (Constitutional Law, for which Kortmann received the Thorkbecke Prize in 1996), Het staatsrecht van de landen van de Europese Unie (Constitutional law of the Member States of the European Union), and Het bestuursrecht van de landen der Europese Gemeenschappen (Public Law of the Member States of the European Communities) are amongst his most important publications.
In 2005, the second chamber of the Dutch parliament appointed him to be the chairman of the referendum committee on the rejected Treaty establishing a Constitution for Europe.
[3] Kortmann was asked regularly to give advice and explanation in matters of public law in Dutch media.