Odo of Bayeux v Lanfranc (1071) is the modern name of a very early (and pre-common law trial in English law. It involved a dispute between Lanfranc of Canterbury Archbishop of Canterbury and Odo, Bishop of Bayeux and brother of William the Conqueror. The trial is basically an appeal against the landmark Trial of Penenden Heath case heard earlier that same year.
The three day trial Trial of Penenden Heath (1071) was heard before Geoffrey, Bishop of Coutance, and resulted in the restoration of many manorial estates of the bishopric at Canterbury, and a clarification of the ancient customs of the kingdom of Kent, which had brokered many privileges from the conqueror in exchange for Kents support of William in his invasion. This first trial was unusual in calling legal experts from both English and Norman Law.
After the first trial Odo sought an action to have the decision annulled. This suit, supported and heard by William was successful for Odo. Lanfranc appealed to the court on the basis of an error in the pleadings but Odo was still successful.
The court cases can be viewed as a part of a large collection of pleadings against a process of Nomanization that within a decade saw 64% of land in England consolidated into the hands of just 150 individuals, and many of the nobility deprived of their estates.