https://www.scconline.com/blog/post/2019/01/29/scotus-secret-sales-can-invalidate-a-patent-petitioner-denied-patent-rights-over-an-invention-which-was-available-to-public-use-prior-to-patent/
SCOTUS | "Secret sales" can invalidate a patent; petitioner denied patent rights over an invention which was available to public use prior to patent