Priveligium Fori - "privilege of the forum"
This was about the ancient rights of certain classes of defendants to be tried in courts comprised of their peers. The Privilegium Fori is Latin for the "Privilege of the (legal) forum".
Typically, it is the application of the principle of trial by one's peers, either by such a jury or at least by a specific court belonging to a particular social segment or class, such as that a soldier might be tried by a court martial, or a cleric by a canonical or ecclesiastical court.
In Canon Law this term was used to decribe the right of clerical immunity from secular justice, later known as the Benefit of the Clergy. Members of the clergy, for instance, in some regions in Europe had the right to be tried by a special tribunal in civil and criminal cases to be held before an ecclesiastical judge.
Pope Urban II restates this right in a letter
"no secular lord is permitted to have power over clerks; but all clerks must be subject to their bishop alone."
David Luscombe; Jonathan Riley-Smith (14 October 2004). The New Cambridge Medieval History: Volume 4, c.1024-c.1198. Cambridge University Press. pp. 439–. ISBN 978-0-521-41410-4.
Urbani II. Epiit. 14. ad Rodulphum comitem (Mansi XX. p. 659):
Nosse te volumus, quia nulli saecularium domino potestatem in clericos habere licet ; sed omnes clerici Episcopo soli esse debent subjecti.
Johann Karl Ludwig Gieseler (1853). A compendium of ecclesiastical history. T. & T. Clark. pp. 190–.
The principle Priveligium Fori is the very question central to the issues raised by the Constitutions of Clarendon, which are themselves seen as a kind of Anglo-Saxon thinking reaching deep into the design of the English Constitution, which is later seen more obviously in the some of the clauses of Magna Carta. Some see Clarendon as the beginning where England was rescued from the vassalage of Rome. The issue in the Constitutions of Clarendon was how far English custom could evade the privilegium fori of the clergy.
(1911). Ecclesiastical Privileges. In The Catholic Encyclopedia. New York: Robert Appleton Company. Retrieved September 15, 2012 from New Advent: http://www.newadvent.org/cathen/12437a.htm
(1910). Ecclesiastical Jurisdiction. In The Catholic Encyclopedia. http://www.newadvent.org/cathen/08567a.htm
Domingos Sequeira (2004). Os presbíteros diocesanos e o seu envolvimento na política: proibição e excepção : estudo histórico-canónico-teológico. Gregorian&Biblical BookShop. pp. 50–. ISBN 978-88-7652-978-8.
Extract from a dissertation
Melodie Harris Eichbauer, The Catholic University of America, Washington D.C. "The Evolution of Gratian's Decretum: From Teaching Tool to Comprehensive Code of Canon Law"
In the end, Gratian concluded that canon and public laws exempted clerics from civil judgment in both civil and criminal cases.
While both secular and ecclesiastical courts possessed their own sphere of influence, a privilegium fori exempted clerics from secular jurisdiction. This norm, according to Chodorow, derived from Paul’s admonition that a cleric, as a soldier of God, did not entangle himself in secular business (2 Tim. 2:4).
Gratian continued by stating that a cleric could not go before a civil judge, unless perhaps
the bishop either did not want to decide a civil case or he stripped the cleric, deemed a
criminal, of his honorary belt.
Relying on the words of Clement, Gratian refined his argument to distinguish between secular business and the business of secular men.
Clerics were prohibited from engaging in the business of secular men but not from engaging in secular matters. The business of clerics, whether civil or criminal, was the prerogative of ecclesiastical judgment.
It was common for clerics to manage ecclesiastical property and thus be involved in secular matters. A bishop, however, could judge such cases if they involved a cleric.
Henry Charles Lea (1869). "Benefit of Clergy". Studies in church history: The rise of the temporal power.--Benefit of clergy.--Excommunication. H. C. Lea. pp. 169–.
David Luscombe; Jonathan Riley-Smith (14 October 2004). The New Cambridge Medieval History: Volume 4, c.1024-c.1198. Cambridge University Press. pp. 438–.
The Punishment of Felonous Clerks
by C. R. Cheney
The English Historical Review
Vol. 51, No. 202 (Apr., 1936), pp. 215-236
The Becket Controversy in Recent Historiography
by James W. Alexander
Journal of British Studies
Vol. 9, No. 2 (May, 1970), pp. 1-26
Review: Thomas Becket, Höfling und Heiliger
by Frank Barlow
English Historical Review (April 2005) 120 (486): 500.
The Becket Dispute and the Criminous Clerks
by Charles Duggan
Volume 1 and 2: Le privilegium fori en France du décret de Gratien à la fin du XIVe siècle - Génestal, Robert,
The Assize "Utrum" and Canon Law in England
by Samuel E. Thorne
Columbia Law Review
Vol. 33, No. 3 (Mar., 1933), pp. 428-436
Archive.org copy: The Canon law in Mediaeval England, an examination of William Lyndwood's Provinciale,
THE CANON LAW IN MEDIEVAL ENGLAND. » 29 Jun 1912 » The Spectator Archive
Dorothy Mary Owen; Michael J. Franklin; Christopher Harper-Bill (1995). Medieval Ecclesiastical Studies: In Honour of Dorothy M. Owen. Boydell & Brewer Ltd. pp. 165–. ISBN 978-0-85115-384-1.
Robert SOUTHEY (1826). Letters to Charles Butler,Esq. comprising essays on the Romish religion and vindicating The Book of the Church. Letter VIII Thomas a Becket: John Murray. pp. 345–.
Benefit of clergy - Wikipedia