New York has long recognized the common law rule of completeness. See Rouse v. Whited, 25 NY 170, 174-175 (1862) (tracing the rule back to its earliest roots in New York in the early 1800s). As set forth in the Guide to New York Evidence Rule 4.03, the rule provides as follows: “When part of a writing, conversation, recorded statement or testimony, or evidence of part of a transaction is admitted, any other part of that writing, conversation, recorded statement or testimony, or evidence of any other part of the transaction, may be admitted when necessary to complete, explain, or clarify the previously admitted part. The timing of the admission of such additional parts is subject to the court’s discretion.”

The rule recognizes that evidence that has been introduced may be so related to other evidence not yet introduced that in fairness both should be considered together, and that in some instances such consideration should be contemporaneous. Note to Guide Rule 4.03. As stated by the Court of Appeals, the rule is founded upon “the plainest principles of equity.” Rouse, 25 NY at 177.