In a rare win for Blackberry-maker Research in Motion, the U.S. Court of Appeals for the Federal Circuit, affirming the district court, disavowed the doctrine of claim differentiation in favor of a "very important" claim limitation in the specification. Inpro Licensing, S.A.R.L. v. T-Mobile USA, Inc., Research in Motion Limited and Research in Motion Corporation (collectively "RIM"), Case No. 05-1233 (Fed. Cir. May 11, 2006) (Newman, C.J.).
Inpro accused RIM of infringing its patent for a credit-card-sized personal digital assistant that communicates with a host computer. Inpro appealed the district court’s interpretation of three claim terms, including the term "host interface." The district court had interpreted "host interface" as "a direct parallel bus interface." Inpro conceded that if the district court’s interpretation of "host interface" was correct, infringement would not lie.
Inpro argued that under the doctrine of claim differentiation, the limitations of "host interface" in some unasserted claims demonstrate that the broader asserted claims are not limited to a "direct parallel bus interface" but include any interface (serial or parallel, direct or indirect) for communicating with the host. Rejecting application of the doctrine of claim differentiation, the Court stated that describing claims in different words "does not invariably change the scope of the claim." Citing the recent Phillips case, the Court recognized the boundaries of patented inventions are contained in the claims but construed in light of the specification, prior art and prosecution history.
Turning to the patent, the Court found that Inpro had referred to communication with the host by serial connection as "a big drawback" and "very troublesome" while it referred to communication with the host by "direct parallel bus interface" as a "very important feature" of the invention. The Court also found that the prosecution history of related applications supported the view that "host interface" requires "a direct parallel bus interface."
Judge Newman wrote the majority opinion and also added a separate concurrence concerning the Court’s failure to review the two remaining terms. Judge Newman argued that the interests of the parties and the public, as well as judicial economy, required disposition of all issues of claim construction raised on appeal. Given the fact the Court had "done most of the judicial work anyway," Judge Newman argued that all three claim terms should have been reviewed and decided on appeal "lest our silence leave a cloud of uncertainty on the patent, its scope, and its validity."
Practice Note
Using strong language in a patent application that refers to inferior embodiments as "a big drawback" or "very troublesome," while referring to the preferred embodiment as "important" or "very important," may be used to limit asserted claims.
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