What is the main stipulation of 35 U.S.C. § 102(d)?

The main stipulation of 35 U.S.C. § 102(d) is that a patent cannot be obtained if the invention was already patented in a foreign country before the U.S. application was filed. This provision is aimed at maintaining the uniqueness and novelty of inventions for which a patent is sought in the United States. It ensures that an inventor cannot claim rights to an invention in the U.S. that has already been publicly disclosed or claimed by another party in a foreign patent. This helps to prevent a scenario where an inventor tries to gain patent protection in the U.S. after having already disclosed the invention or patented it abroad, thereby promoting fairness and integrity in the patent system.

While some of the other options touch on relevant aspects of U.S. patent law, they do not accurately encapsulate the specific requirements and intentions of this statute, which focuses on the consequences of prior foreign patents on the ability to secure U.S. patent rights.