Eliseo Aja was born in Santander in 1946. He studied law in the Universidad de Valladolid, he was doctorated in 1973 in the Universitat Autònoma de Barcelona and since 1983 he is professor of Constitutional Law in the Universitat de Barcelona.
Below there are the main books that he has published or directed:
- Democracia y socialismo en el siglo XIX español, Madrid, 1976, Edicusa.
- Constituciones y periodos constituyentes en España (1808-1936), with J. Solé Tura, Madrid, 1977, Siglo XXI.
- El sistema jurídico de las Comunidades Autónomas, Madrid, 1985, Tecnos.
- Las tensiones entre el Tribunal Constitucional y el Legislador, Barcelona, 1998, Ariel.
- El Estado autonómico. Federalismo y hechos diferenciales, Madrid, 1999, Alianza
- Veinte años de inmigración en España, amb J. Arango, Barcelona, 2006, Cidob.
He has also been coauthor of the following books:
- Informe sobre las autonomías, directed by J. Tornos, Madrid, 1988.
- El futuro de las autonomías territoriales, with L. Martín Rebollo, Santander, 1991.
- La riforma delle autonomie regionali, Torino, 1995;
- Federalism and Civil Societies, with J. Kramer/H.P.Schneider, Baden-Baden, 1999.
- Dimensions of local and regional democracy, with J. Loughlin, Oxford University Press, 2000.
- Comparative study of EU Member States immigration legislation, with B. Nacisbene, Giuffré Ed., 2001.
He has taken part in different advisory committees for constitutional and legislative reforms, especially in matters of regionalism, in different European and Latin American countries. And he has also been called by the Parliament so that he, as an expert, can inform about the constitutional reform of the Senate (1995) and sometimes for evaluating the regulation on immigration. Also he has attende as an expert to the Parlament de Catalunya and other autonomic legislative assemblies.
He has been the director of the Informe de las Comunidades Autónomas (report on the Autonomous Communities), and author of the "Valoración general" that is at the beginning of each anual volume between 1989 and 1998 and has been the director of the Institut de Dret Públic de Barcelona since 2001 until 2009.
In 2005 he was elected president of the Associació de Constitucionalistes d'Espanya (2005-2008) and in 2009 he was appointed member of the Consell de Garanties Estatutàries de Catalunya by the government of the Generalitat de Catalunya, and he was elected president unanimously by all the members for the period 2009-2013.