Our country’s patent laws have long been founded on the premise of a bargain, a quid pro quo—that in exchange for receiving patent rights allowing an inventor to exclude others from making, using or selling an invention, the inventor needs to show all his or her cards, to tell the world not only what the invention is (and its true scope) but also how best to make it. In this way, the public can best understand the invention and be placed in the best position to improve upon it, genuinely accomplishing our Constitution’s goal of promoting the progress of science. Const. Art. I, Sect. 8. This premise is purportedly codified in 35 U.S.C. §112, which requires all patents to contain a “full, clear, concise, and exact” “written description” of the invention. What exactly this means and whether it requires something different from “enabling” the invention, is still open to debate.

On Aug. 21, 2009, the U.S. Court of Appeals for the Federal Circuit granted Ariad Pharmaceuticals, Inc.’s (Ariad) petition for rehearing en banc of the court’s April 3, 2009 decision in the appeal of Ariad Pharmaceuticals, Inc. v. Eli Lilly and Company (Lilly).1 The en banc rehearing of a three-judge panel decision sets the stage for the Federal Circuit to provide clarification for, and potentially a drastic change to, the court’s written description jurisprudence. Specifically the court will address two issues:

• Whether 35 U.S.C. §112 paragraph 1, contains a written description requirement separate from an enablement requirement?2

• If a separate written description requirement is set forth in the statute, what is the scope and purpose of the requirement?3