YA'U v state (2012) LPELR 20798 CA
CRIMINAL LAW AND PROCEDURE - ARRAIGNMENT OF AN ACCUSED PERSON: Requirements of a valid arraignment 

"The requirement for arraignment is not optional but mandatory. The failure by a Court to observe the procedure would render the entire proceedings a nullity ab initio. See Sanmabo v. The State (supra). In Udo v. State (2006) 15 NWLR (Pt. 1001) 179 at 189-190 the Supreme Court reiterated the requirements of a valid arraignment as follows: "(a). That the accused must be placed before the Court unfettered: (b). The charge or information shall be read over and explained to him to the satisfaction of the court by the Registrar or other officer of the Court. (c). The accused shall then be called upon to plead instantly to the charge, unless there is a valid reason not to do so". These three requirements above must co-exist and failure to comply with any one of them will render the trial a nullity. 

Source: law pavilion