A fundamental tenet of appellate practice is that the rights of the litigants are to be determined solely on the basis of materials contained between the covers of the record on appeal. With some rare exceptions discussed below, it is a serious breach of appellate decorum to refer to matters outside the record. Counsel who do so run the risk of being reprimanded by the court during oral argument and in a subsequent published opinion.

References in briefs to material not contained in the record may be stricken on motion made by the opposing party and, if granted, this may blemish the offending counsel’s reputation for integrity and reliability before the panel that will decide the appeal. The court may also deny costs to a prevailing party whose brief contained references to matters outside the record. Topal v. Pace University, 167 A.D.2d 387 (2d Dept. 1990) (“since the appendix to the defendant’s brief contains documents dehors the record, the defendant is denied costs on appeal”). This may amount to a significant loss for the prevailing party, far in excess of the $250 statutory costs (CPLR §8203[a]), because the party awarded costs is also entitled to recover its taxable disbursements, including the reasonable cost of printing the record on appeal and briefs. CPLR §8301(a)(6),