In a March 22, 2010 decision, the Court of Appeals for the Federal Circuit held en banc that there are separate written description and enablement requirements in the U.S. Patent Law. The decision is Ariad Pharm., Inc. v. Eli Lilly & Co., ___F.3d ___, No. 2008-1248 (Fed. Cir. Mar. 22, 2010) (en banc). (Note: “en banc” means “by the full court” or “full bench.” When all the members of an appellate court hear an argument, not a panel of three judges, the court is then said to be sitting en banc.)

As reported in another edition of this newsletter, in an earlier case on April 3, 2009, the Federal Circuit invalidated Ariad Pharmaceuticals, Inc.’s (Ariad’s) U.S. Patent No. 6,410,516 for failure to meet the “written description” requirement of the U.S. Patent Law recited at Title 35 U.S.C. § 112, ¶ 1. The earlier case is Ariad Pharm., Inc. v. Eli Lilly & Co., 560 F.3d 1366 (Fed. Cir. 2009). Ariad then petitioned for a rehearing with the Federal Circuit en banc. Ariad argued that the written description requirement was not separate from the enablement requirement of Section 112 of the U.S. Patent Law. On August 26, 2009, the Federal Circuit granted Ariad’s motion for a rehearing of the case en banc to reconsider the issue of whether 35 U.S.C. § 112 ¶ 1 includes a written description requirement separate from the enablement requirement, and if so, what the scope and purpose of the written description requirement are.  

Section 112 of the U.S. Patent Law sets forth the disclosure requirements with which the patent applicant must comply: (1) the specification must contain a written description of the invention, i.e., the inventor must adequately describe the invention; (2) the applicant must describe the manner and process of making and using the invention so as to enable one of skill in the art to make and use the invention; and (3) the applicant must describe the best mode contemplated by the inventor for carrying out his or her invention. U.S. case law has historically interpreted the written description requirement of the first paragraph of section 112 to be separate and distinct from the enablement requirement, thus requiring a separate analysis.  

In the March 2010 Ariad case, sitting en banc the Federal Circuit reaffirmed its earlier Ariad decision. The Federal Circuit confirmed en banc that Section 112 of the U.S. Patent Law requires separate written description and enablement requirements. Further, as a test for the written description requirement, the Federal Circuit explained that the “test for sufficiency is whether the disclosure of the application relied upon reasonably conveys to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date.” The Federal Circuit further clarified the meaning of possession to mean “possession as shown in the disclosure.”  

In addition, the Federal Circuit indicated that “a few broad principles that hold true across all cases” determine the sufficiency of written description. First, “the written description requirement does not demand either examples or an actual reduction to practice; a constructive reduction to practice that in a definite way identifies the claimed invention can satisfy the written description requirement.” Second, “actual ‘possession’ or reduction to practice outside of the specification is not enough . . . it is the specification itself that must demonstrate possession.” Third, “a description that merely renders the invention obvious does not satisfy the requirement.”  

The Federal Circuit also noted that it is possible for a patent specification to enable the use and practice of a claimed invention, yet still not describe the invention in sufficient detail so as to satisfy the written description requirement. In particular, the Federal Circuit recognized that “there is little difference in some fields between describing an invention and enabling one to make and use it, but that is not always true of certain inventions, including chemical and chemical-like inventions.” The Federal Circuit explained that “although written description and enablement often rise and fall together, requiring a written description of the invention plays a vital role in curtailing claims that do not require undue experimentation to make and use, and thus satisfy enablement, but that have not been invented, and thus cannot be described.”  

A copy of the opinion may be found at