On June 12, 2014, the US Court of Appeals for the Federal Circuit issued a precedential opinion affirming the obviousness of a patent claim directed to a drug molecule. Bristol-Myers Squibb Co. v. Teva Pharms. USA, Inc., ___ F.3d ___ (2014). This is an example of the Federal Circuit holding a molecule patent invalid for obviousness.

The Federal Circuit upheld US District Court for the District of Delaware Magistrate Judge Christopher Burke's opinion that held claim 8 of U.S. Patent No. 5,206,244 invalid in light of a structurally similar molecule. Claim 8 covers the entecavir molecule, which is the active ingredient in BMS' Baraclude® tablets, which are designed to treat hepatitis B virus (HBV) infection. Teva successfully argued that one of ordinary skill in the art seeking to make an anti-HBV drug in October 1990 would have selected a prior art compound called 2'-CDG as a "lead compound" and would have modified it by adding a methylene (i.e. carbon-carbon double bond) group as indicated in the diagram to the right, below.