oyer (oy-<>r oroh-y<>r). [fr. Old French oïr “to hear”] Hist. 1.A criminal trial held under a commission of oyer and terminer. See COMMISSION OF OYER AND TERMINER. 2. The reading in open court of a document (esp. a deed) that is demanded by one party and read by the other. 3.Common-law pleading. A prayer to the court by a party opposing a profert, asking to have the instrument on which the opponent relies read aloud. • Oyer can be demanded only when a profert has been properly made, but it is disallowed for a private writing under seal. [Cases: Bills and Notes 488; Pleading 306. C.J.S. Bills and Notes; Letters of Credit
§§ 267, 293; Pleading §§ 520–522.]

“A party having a right to demand oyer is yet not obliged, in all cases, to exercise that right; nor is he obliged, in all cases, after demanding it, to notice it in the pleading he afterwards files or delivers. Sometimes, however, he is obliged to do both, namely, where he has occasion to found his answer upon any matter contained in the deed of which profert is made, and not set forth by his adversary. In these cases the only admissible method of making such matter appear to the court is to demand oyer, and, from the copy given, set forth the whole deed verbatim in his pleading.” Benjamin J. Shipman, Handbook of Common-Law Pleading § 289, at 483 (Henry Winthrop Ballantine ed., 3d ed. 1923).
[Blacks Law 8th]