Claim Differentiation in Continuation Application Supports Broader Construction

The Saunders Group, Inc. v. Comfortrac, Inc., [2006-1576](June 27, 2007)[BRYSON, Michel, and Dyk] The Federal Circuit reversed the grant of summary judgment of non-infringement of U.S. Patent No. 6,899,690 on a lightweight cervical traction device because the district court's claim construction was erroneous.
SIGNIFICANCE: (1) Claim differentiation in continuation application supports broader construction for claims without claim term. (2) Arguments in a parent application about claim language that is missing from the continuation appliaction do not affect the scope of the continuation application. (3) Validity concerns are not a basis to restrict the interpretation of claims from their proper construction.
BRIEF: The district court construed the term "pneumatic cylinder" to include at least one pressure activated seal, even though a pressure activated seal was specifically recited in some of the claims and not recited in other of the claims. The Federal Circuit observed that claim terms are generally given the meaning those terms would have to a person of ordinary skill in the art, and found that it was not disputed that "pneumatic cylinder" does not require "pressure activated seals". The Federal Circuit said that claims can be assigned a narrower scope only if there is an indication in the patent or the prosecution history, and the Federal Circuit found no such indication. In fact, because a dependent claim included a pressure activated seal, the Federal Circuit found that the doctrine of claim differentiation supported the inference that claim 1 encompasses cylinders without a pressure activated seal, because otherwise the claims would have identical scope. The Federal Circuit rejected the argument that additional language in the dependent claim provided meaningful difference in scope, finding that it was simply definitional language. The Federal Circuit also found that the prosecution history supported the broader interpretation of the claims, noting that when the patentees filed the continuation application, the omitted the limitation from some but not all of the new claims. The Federal Circuit said that had they omitted the limitation from all of the claims, there might have been be an argument that the limitation was assumed to be present and need not be recited, but by making the change to only some of the claims, there is a strong indication that the claims without the pressure seal limitation to not include it. The Federal Circuit also found support in the Petition to Make Special, which only identified the claims without the pressure seal as covering defendant's product without a pressure seal, as indicating the intentional difference in claim scope.
In response to defendant's argument that the claims must be limited to embodiments with pressure activated seals because not other embodiments were described, the Federal Circuit said that the patent nowhere indicated that the pressure activated seal is the only way to maintain the needed traction force. The Federal Circuit seems to have skirted the enablement question. The Federal Circuit also rejected the argument based upon the prosecution history of the parent application, because all of the claims in the parent application had the requirement of the pressure activated seal, unlike the claims in the patent in suit. "When the purported disclaimers are directed to specific claim terms that have been omitted or materially altered in subsequent applications (rather than to the invention itself), those disclaimers do not apply."
The Federal Circuit rejected the use of avoiding invalidity as a claim construction tool.
The Federal Circuit concluded with a commentary on the difficulty of claim construction, and reversed the district court's construction.