N.Y.C. Admin. Code § 20-474.3: § 20-474.3 Failure to produce license; presumptive evidence of unlicensed activity.

a. In any action or proceeding, failure by a general vendor who is required to be licensed pursuant to the provisions of this subchapter to exhibit upon demand a general vendor's license in accordance with the provisions of this subchapter to any police officer or authorized officer or employee of the department or other city agency shall be presumptive evidence that such general vendor is not duly licensed.

b. In any action or proceeding, failure by any person who is required to obtain a distributor's license pursuant to the provisions of this subchapter, or failure by the driver of such person, to exhibit upon demand a distributor's license in accordance with the provisions of this subchapter to any police officer or authorized officer or employee of the department or other city agency shall be presumptive evidence that such person is not duly licensed.