Skip to main content
CAFC Updates


By March 16, 2022No Comments

Judges Lourie, Moore, and Newman dissent from the denial of Biogen’s petition for rehearing en banc because in their view the panel majority has affirmed a district court’s erroneous broadening of the written description inquiry that imports extraneous considerations into the written description analysis and blurs the boundaries between the written description requirement and the other statutory requirements for patentability. The district court found and the CAFC previously affirmed that Mylan met its burden of proving by clear and convincing evidence that the specification of Biogen’s U.S. Patent 8,399,514 (directed to a method of treating multiple sclerosis by orally administering dimethyl fumarate, monomethyl fumarate, or a combination thereof) failed to demonstrate to a person of ordinary skill in the art that the inventors invented what is claimed. The dissenting judges believe that the panel majority and the district court: 1) overly emphasized unclaimed disclosures in the specification; 2) erroneously imposed a heightened burden on the patentee to show that the specification proves efficacy; 3) imported legal factors from other patentability requirements; and 4) were influenced by irrelevant extrinsic evidence. The dissenting judges submit that by denying rehearing en banc, the CAFC has lost an opportunity to provide clarity for future litigants by reaffirming the proper boundaries of the written description requirement in 35 U.S.C. § 112, and has contributed to the muddying of the written description requirement.

View Decision.