Han Nijdam, Ph.D. (2008), Leiden University, is researcher for Old Frisian at the Fryske Akademy, Leeuwarden.He has published on medieval Frisia and medieval Frisian law, including Wat is Recht? De receptie van Oudfries recht in de Groninger Ommelanden in de 15e en 16e eeuw (Bornmeer, 2018).Jan Hallebeek, Ph.D. (1986), Utrecht University, is professor emeritus of Legal History at the Vrije Universiteit Amsterdam, and extraordinary professor on ‘Ancient structures of the Catholic Church’ at Utrecht University (1997-2006). He has published on medieval Roman and Canon law and early modern scholasticism, including The Concept of Unjust Enrichment in Late Scholasticism (1996).Hylkje de Jong, Ph.D. (2008), Rijksuniversiteit Groningen, is Professor of Legal History at the Vrije Universiteit Amsterdam. She has published on the reception of Roman law in Frisia and on Byzantine law, including Ἐντολή (mandatum) in den Basiliken (Brill, 2019).