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Claim Term “Comprising” Permits Process Steps Using Temperatures Outside of Claimed Range

May 07, 2003

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Last Month at the Federal Circuit - June/July 2003

Judges:  Rader (author), Bryson, and Dyk

The Federal Circuit vacated a SJ finding of noninfringement in Invitrogen Corp. v. Biocrest Manufacturing, L.P., No. 02-1207 (Fed. Cir. May 7, 2003), after finding error with the district court’s claim construction.

Invitrogen Corporation (“Invitrogen”) filed suit against Biocrest Manufacturing, L.P. and others (collectively “Biocrest”) in the U.S. District Court for the Western District of Texas, asserting numerous claims of its U.S. Patent No. 4,981,797 (“the ‘797 patent”), directed to a method for growing E. coli bacteria. According to the district court’s claim construction, the claimed method required a growing step that was limited to a specified temperature range and excluded growing in temperatures outside that range. Applying that construction, the district court granted SJ of no infringement, because the accused method included a preliminary growing step under temperature conditions outside the claimed range. The Federal Circuit vacated that ruling, holding that the claim term “comprising” left open the possibility of growing steps outside the claimed range and that the district court failed to read the claim in the context of the relevant scientific field.

E. coli
is a bacteria commonly used in DNA technology to produce beneficial proteins. The ‘797 patent claims a process for making E. coli cells with an enhanced capacity to accept foreign DNA with increased competence (the cell’s capacity for accepting foreign DNA). In relevant part, claim 1 of the ‘797 patent claims “a process for producing transformable E. coli cells of improved competence by a process comprising . . . growing E. coli cells in a growth-conducive medium at a temperature of 18°C to 32°C . . . .” In rejecting the original application claim directed to a temperature range of “less than 37°C,” the Examiner stated that the range of 18°C to 32°C was essential to the invention. In response, the applicant amended the claim to include that range and also noted that the invention avoids undesirable growth effects at 37°C. Based on this prosecution history, the district court concluded that the applicant disclaimed all growth outside the range of 18°C to 32°C.

The Federal Circuit disagreed, explaining that the transition “comprising” indicates that the claim is open-ended and allows for additional steps, including steps that produce E. coli growth before the recited steps. Thus, the claim itself does not preclude other growth.

Additionally, to illuminate the claims’ meaning and reach, the Court considered the context of the scientific field embodied in the patent specification. For example, the specification discussed the preparation of master seeds (E. coli cells in long-term frozen storage that are processed into primary seeds that are used in the claimed method) by growing the E. coli cells at 37°C.

With respect to the prosecution history relied upon by the district court, the Federal Circuit concluded that during prosecution, the applicant simply specified the growing requirements for achieving competence in the cells. The Federal Circuit also noted that during prosecution, the applicant did not address growth at 37°C that occurs before initiation of the claimed method. Accordingly, the Federal Circuit held that the claim scope does not preclude preparatory steps in advance of the claimed growing step at a temperature outside the claimed range of 18°C to 32°C.

Invitrogen also disputed the district court’s claim construction that the preamble term “improved competence” limited the claims, arguing that the preamble term should not be limiting because it simply stated an intended advantage. Biocrest countered that while the district court had correctly concluded that the preamble term was a claim limitation, it should have further construed the term to require at least a ten-fold increase in competence. The Federal Circuit upheld the district court’s construction, agreeing that the preamble term acted as a limitation, because, during prosecution, the applicant had clearly relied on the preamble to distinguish the invention from the prior art. Specifically, in overcoming a rejection of claims that did not require increased competency, the applicant amended the preamble to recite “improved competence” and repeatedly argued that this feature distinguished the invention from the prior art. The Federal Circuit further found that the district court had correctly consulted the overall context of the claim language to determine the limiting effect of the claim language and test data in the prosecution history and patent specification showing varying amounts of increased competence. For these reasons, and because neither the claim language, specification, nor prosecution history contained any specific numerical limitation, the Federal Circuit upheld the district court’s construction of the preamble term “increased competence.”