Stefán is an Icelandic-qualified attorney with rights of audience before the Icelandic Supreme Court. He completed an LL.M. in commercial law from Cambridge University in 2008. Stefán has worked as a lawyer since 2005 and is a part-time lecturer at the law faculty of Reykjavík University, where he teaches legal procedure and the law of obligations. Stefán was previously vice-president of the Icelandic Bar Association. In 2024 he was elected president of the Icelandic Bar Association.
Stefán has pleaded many cases before both the Icelandic courts and the EFTA court. He has also acted on a number of occasions as an expert witness on matters of Icelandic law before foreign courts and tribunals.
Stefán has repeatedly been recognised by the leading international legal directories, including Chambers & Partners and Legal500, as one of Iceland’s most highly regarded and recommended lawyers.