Dr Accetto graduated from the Faculty of Law of the University of Ljubljana in 2000 and obtained a doctorate in law from the same Faculty in 2006. He further obtained an LL.M. from Harvard Law School in 2001. After obtaining his doctorate in law in 2006, he received a Monica Partridge Visiting Fellowship and spent the Easter term at Fitzwilliam College of the University of Cambridge as a visiting lecturer. In 2011 he completed a longer research visit at Waseda University in Tokyo, and in 2012 he was a visiting scholar at the Faculty of Law of the University of Cambridge.
During his doctoral studies he worked at the Institute for Comparative Law of the Faculty of Law of the University of Ljubljana as a young researcher, and from 2008 at the Faculty of Law of the University of Ljubljana as an assistant professor of EU law, and from 2013 as an associate professor of EU law. From September 2013 until August 2016 he lectured at the international graduate law school Católica Global School of Law / UCP in Lisbon as a professor with an additional research grant from the Gulbenkian Foundation, and since the beginning of the 2016/17 academic year he has been lecturing at the Faculty of Law of the University of Ljubljana.
In addition to his regular lectures in Slovenia and Portugal, he taught entire courses or held a series of lectures as a guest lecturer at the Graduate School of the Chinese Academy of Social Sciences in Beijing (China), Irkutsk State University (Russia), and the ISES Foundation in Kőszeg (Hungary), and at the Católica University in Lisbon (Portugal) also before 2013. He has delivered occasional guest lectures, inter alia, at Harvard University (Harvard Law School and Harvard Kennedy School, USA), the University of Copenhagen (Denmark), Tokyo Waseda University and the University of Kyoto (Japan), the University of Graz (Austria), the University of Iceland (Iceland), the University of Kaunas (Lithuania), the Faculty of Law in Bihać (Bosnia and Herzegovina), and Franklin College (Switzerland). He continues to lecture at the Faculty of Law of the University of Ljubljana and the Católica University in Lisbon as an external staff member.
While concentrating mainly on his research and pedagogical work, he has also cooperated with the judiciary and jurisprudence in various ways. In 2003 he spent five months at the Court of the European Union as a trainee, and in the period 2003/04, as a Fellow of the British Lord Slynn Foundation for European Law, he spent a year working with distinguished British judges (the House of Lords (which at that time still functioned as the court of last resort), the Commercial Court, the Central Criminal Court), attorneys (the Brick Court Chambers, Blackstone Chambers, Doughty Street Chambers), and law firms (Clifford Chance, Ashurst). Between 2007 and 2011 he was, inter alia, a member of the National Commission for the Legal Revision of the Historic Case Law of the European Court of Justice, and between 2009 and 2013 he was president of an examination board for the examination of court interpreter candidates as well as a lecturer at events organised by the Slovene Judicial Training Centre.
He has participated in numerous national and international research projects that focused on different issues of fundamental rights, (constitutional) adjudication, and citizenship. He is the author of several books and numerous scientific legal papers (in Slovene, English, and Portuguese) as well as numerous editorials and columns in legal newspapers and on websites.
He commenced duties as judge of the Constitutional Court on 27 March 2017 and assumed the office of Vice President of the Constitutional Court on 28 September 2019. He assumed the office of President of the Constitutional Court on 16 December 2021.