Evidence of Routine Practice In New York
In New York, proof of a business, professional or other institutional practice or custom is admissible to show that the practice or custom was or would have been followed under the same set of circumstances on a specific occasion (Soltis v. State of New York, 188 AD2d 201, 594 NYS2d 433 [3d Dept 1993]).
In other words, evidence of a routine practice is admissible as circumstantial evidence that an individual acted in conformity with his routine practice on the date in question (Rigie v. Goldman, 148 AD2d 23, 543 NYS2d 983 [2d Dept 1989]).
As recognized by the Court of Appeals, "[c]ircumstantial proof is, of course, as probative as direct evidence and may be even more persuasive" (New York State Assn. of Counties v. Axelrod, 78 NY2d 158, 577 NE2d 16, 573 NYS2d 25  citing 1A Wigmore, Evidence 26, at 957, 961 [Tillers rev 1983]).
Further, the admissibility of business, professional or other institutional custom or practice is not limited to instances where the witness is to testify solely to a personal habit or custom and was in total control of the circumstances.
Rather, an employee may testify to the custom and practice of his organization as probative evidence of the conduct of other employees of the organization on a given occasion (Soltis v. State).