Claim Differentiation Shows that Cylinder Did Not Require Seals Despite Parent Application Where All Cylinders Had Seals

Case: Saunders Group, Inc. v. Comfortrac, Inc., No. 2006-1576 (U.S. Fed. Circuit Court of Appeals, June 27, 2007)


The One Sentence Summary: In a dispute about cervical traction devices, summary judgment of non-infringement is reversed where the district court's claim construction was erroneous because a limitation from the claims of a parent patent should not have been used to limit the descendant patent's claims resulting from the continuation application.

Federal Circuit Holdings:

• The district court erred in claim construction in determining that all claims of the patent should be interpreted to have a "pressure activated seal" as part of a "pneumatic cylinder."
  
• Claim differentiation supported the plaintiff's argument that claim 1 was not limited because dependent claim 6 added a limitation of a pressure activated seal.
• The specification did not limit the claims even though the specification described only pneumatic cylinders with pressure activated seals. Here, the claim language clearly covered cylinders without pressure activated seals even though only a single embodiment (with seals) was described in the specification.
• Language from the parent patent's prosecution history disclaiming cylinders without seals did not limit the scope of the claims in the descendant patent where cylinders without seals were claimed.
• Arguments from the prosecution history of the parent patents about the inability of prior art devices to maintain force did not clearly link that inability to the absence of pressure activated seals in the prior art. Thus, these arguments did not show that the cylinders of the patent always had pressure activated seals.