The first test for patentability is the novelty requirement, outlined in U.S. patent law under 35 U.S.C. § 102. This statute mandates that an invention must be new to be patented. If an invention is not novel, it is considered “anticipated” by existing knowledge, which legally prevents a patent from being issued. This assessment revolves around the concept of “prior art.”

https://legalclarity.org/can-you-patent-something-that-already-exists/

So, you want 35 U.S.C. § 102, which says:

A person shall be entitled to a patent unless —

(a) the invention was known or used by others in this country, or patented or described in a printed publication in this or a foreign country, before the invention thereof by the applicant for patent, or

(emphasis mine).