N.Y. Gen. Bus. Law § 236

§ 236. Prima facie proof. 1. In any action relating to the\nenforcement of any provision of this article, a certificate duly issued\nby an assay office of the treasury department of the United States,\ncertifying the weight of any article, or any part thereof, or of the\nkind, weight, quality, fineness or quantity of any ingredient thereof,\nshall be receivable in evidence as constituting prima facie proof of the\nmatter or matters so certified.\n 2. In any action relating to the enforcement of any provision of this\narticle, proof that an article has been marked in violation of the\nprovisions of this article shall be deemed to be prima facie proof that\nsuch article was manufactured after this article became effective.\n