Revisiting the issue of written description requirement for a genus claim in a biotechnological invention, the U.S. Court of Appeals for the Federal Circuit found that the lower court did not err in holding that the genus claim is invalid for failure to meet a written description requirement. However, the Court held that the district court erred in its decision to invalidate the claims by applying the essential element test in the analysis of written description requirement. Carnegie Mellon University v. Hoffmann-La Roche Inc., Case No. 07-1266; Carnegie Mellon University v. Hoffmann-La Roche Inc., Case No. 07-1267 (Fed. Cir., Sept. 8, 2008) (Lourie, J.).

Carnegie Mellon University is the owner of three patents with claims for a recombinant bacterial plasmid for the enhanced expression of DNA polymerase enzyme. The patent specification disclosed the construction of a recombinant plasmid with E. coli DNA polymerase gene. Hofffmann-La Roche commercially manufactures Taq DNA polymerase using a nucleotide sequence from the bacterium Thermus aquaticus.

In two different suits, Carnegie Mellon asserted that Hoffmann-La Roche infringed three of its patents. Hoffman-La Roche’s motions for summary judgment for invalidity of patent claims were granted in both cases. The district court reached its decision based on two lines of reasoning. First, the patents have generic claims for DNA polymerase gene isolated from “a bacterial source,” while the specification disclosed the details for DNA polymerase gene only from E. coli. The district court held that the generic claims of the patent were invalid for lack of written description for DNA polymerase gene from other bacterial species. Second, the district court also held that the original objective of the invention was to overcome the lethality associated with the unregulated expression of the DNA polymerase and, therefore, under the “essential element” test, the patent claim must contain that feature to overcome lethality as a limitation in order to satisfy the written description requirement. Since the claims did not have that limitation, the court held that claims were invalid.

On appeal, the Federal Circuit affirmed the district court’s grant of summary judgment of invalidity of generic claims. However, the Court concluded that the district court erred in its application of essential element test to find that the claims were invalid.

According to the Court, at the time of invention, DNA polymerase gene had been cloned only from three different bacterial species. It was also known that DNA polymerase is a family of enzymes showing wide variation among bacterial species. Earlier, the Court had held that a description of a genus nucleotide claim may be achieved by means of recitation of representative number of nucleotide sequences that fall within the scope of the genus. Based on these facts, the Court agreed with district court’s conclusion that, in order to meet the written description requirement, the disclosure of a single DNA polymerase gene structure from E. coli was not adequate to support the entire claimed genus. However, the Court noted that this requirement for representative sequence is not an absolute requirement in all cases. The Court pointed out that its earlier decisions requiring a representative number of nucleotide sequences “did not impose a per se rule requiring recitation in the specification of the nucleotide sequence of claimed DNA when the sequence is already known in the field.” But, considering the fact that in the instant case at the time of invention only three bacterial DNA polymerase genes had been cloned and the genus claim covers DNA polymerase from any bacterial species, the Court had to reach the conclusion that the patent specification did not satisfy the written description requirement.

The Court also took the opportunity to clarify the appropriate use for the “essential element” test. According to the Court, the test does not “mandate an inquiry into what an inventor considers to be essential to his invention and requiring that the claims incorporate those elements.” The Court further elaborated that it has applied this test merely to invalidate broad claims in which the specification clearly suggests a narrower scope. Based on this reasoning, the Court held the district court’s application of this test in error given that the lethality was only a reason for the claimed invention rather than an element needing to be defined in the claims.