Regents of the University of California v. Eli Lilly Co. 119 F.3d 1559 (Fed. Cir. 1997) Cal scientists figured out a way to isolate a piece of DNA in rats and use it to create insulin. They filed a patent. The patent was broad and claimed the process for all animals, including humans, even though they had only experimented in rats. When Lilly began making human insulin from human DNA they isolated, Cal sued for infringement. Lilly argued that Cal's patent was not valid under 35 U.S.C. §112 because the written description wasn't detailed to support all of the claims. The written description did not detail the piece of DNA in humans that could be used to make human insulin. The Trial Court found for Lilly. Cal appealed. The Appellate Court affirmed. The Appellate Court found that an adequate written description of DNA requires a precise definition, such as by structure, formula, chemical name, or physical properties. So basically, the Court found that when talking about DNA, you have to specifically spell out the genetic code. Since Cal's patent did not disclose the sequence of human insulin-producing DNA in the written description, Cal could not make a claim for it.