In finding the existence of a contract had not been demonstrated, the Second Department explained the relevant evidentiary rules concerning the authenticity of a document submitted as proof of a contract:
The general rule is that “[a] writing is ordinarily not relevant at trial unless evidence had been introduced to show that it was made, signed or adopted by a particular person” (Prince, Richardson on Evidence, § 9-101 [2008]). “A private document offered to prove the existence of a valid contract cannot be admitted into evidence unless its authenticity and genuineness are first properly established” … . The authenticity of a document may be established by submitting the document with a certificate of acknowledgment …, which was not done here. Nor was any other evidence submitted as to the validity of the documents in issue. Fairlane Fin Corp v Greater Metro Agency, Inc, 2013 NY Slip Op 05875, 9-18-13