Boudewijn Sirks studied Law at the University of Leiden (LLM), followed by studies in Theology and Philosophy at the University of Amsterdam. At the latter university obtained in 1984 a PhD in law.
After working in various positions at the law faculties of Utrecht, Amsterdam and Leiden, he was professor in Legal History and Private Law at the Johann Wolfgang Goethe University in Frankfurt from 1998 till 2006, after which he was Regius Professor of Civil law in Oxford and Fellow of All Souls College. He retired from that chair in 2014. Presently he is an Emeritus Fellow of All Souls College.
Sirks' research interests span Roman law, the law of Late Antiquity, and European private law. He is an editorial member of the Tijdschrift voor Rechtsgeschiedenis (Legal History Review). He was Visiting Scholar at the Columbia University, New York; Visiting Professor at the University of Kansas; and Visiting Professor at the Pontificia Universidad Católica de Chile (Santiago). He is a Corresponding Member of the Royal Netherlands Academy of Arts and Sciences and a Vice-President of the Accademia Romanistica Costantiniana. In 2021 he was awarded the DCL.
- In the fourth and fifth century there are people in the Roman empire who are bound to a particular estate in the sense that the estate owner can recall them and impose services. Their status, called the colonate, is low. Often it is assumed to have been widespread or even a general feature of a general change in agricultural exploitation. Various theories about its cause have been formulated: chronic indebtedness of farmers, fiscal reorganisations, emergence of large estates. However, already in the middle of the third century in Egypt a similar but private law contract existed, the paramonè. The insertion into the census of an estate under Diocletian gave it a public law aspect, making the estate owner now the contract partner. It implied a change in status for the colonus. It was consequently never a general phenomenon.It is a point of contention whether the Theodosian Code contains also obsolete constitutions as foreseen for the projected interim code of CTh 1,1,5, or only valid constitutions (with the exception of Book 16). The text of CTh 1,1,6 is unclear in this point and seems to be a mere continuation of the plan of CTh 1,1,5. However, it appears that the first view does not take into account other statements of Theodosius, and that research into particular subjects shows the compilers have rendered a logically consistent review of the law, without superfluous texts. In view of this evidence it is better to assume that also elsewhere in the Books 1 to 15 as a rule only valid laws were included.