It is a well-established rule of the common law of evidence that a party’s intentional destruction of written evidence relevant to proof of an issue at trial can support an inference that the evidence would have been unfavorable to the party responsible for its destruction. (2 John Henry Wigmore, “Evidence in Trials at Common Law Section 291″ (James H. Chadbourn rev.1979)). 

The New York courts adopted this rule at the beginning of the 20th century and stated it as follows: “… where it appears that a party has destroyed an instrument or document, the presumption arises that if it had been produced it would have been against his interest or in some essential particulars unfavorable to his claims under it. Contra spoliatorem omnia presumuntur. The inference is that the purpose of the party in destroying it was fraudulent. (Joannes v. Bennett, 5 Allen, 169, 172.) (Armour v. Gaffey, (3 Dept., 1898)).