When Is a Cone a Sphere, and Other Applications of the Doctrine of Equivalents

Case: Depuy Spine, Inc. v. Medtronic Sofamor Danek, Inc., No. 05-1311, 05-1335 (Fed. Cir. 11/20/06)

The One Sentence Summary: The Federal Circuit applied the doctrine of equivalents with the "all elements rule," to find, inter alia, that the district court erroneously concluded that there was no question of fact as to whether a cylindrical-conical shape could be equivalent to a spherically-shaped element claimed in a patent for surgical screws, and reversed a grant of summary judgment that had found no infringement.

What They Were Fighting About: At issue were the district court's application of the doctrine of equivalents, and in particular the "all elements rule," in determining whether Medtronic's products infringed Depuy's patent for pedicle screws, used to stabilize spinal column segments during surgery.

Federal Circuit Holdings:

• Summary judgment finding no infringement was reversed as to two groups of Medtronic's screw models, with the Federal Circuit disagreeing with the district court's application of the doctrine of equivalents and the "all elements rule," but sustained as to other models. Medtronic's JMOL was also denied on a jury finding of infringement with respect to one model, and with respect to lost profits.
  
• First, the court agreed there was no literal infringment for two groups of screw models, given that Medtronic's models used a conical, rather than spherical-shape in the receiver member of the device, and in doing so rejected DePuy's argument that because a thin slice of sphere appears conical, the Medtronic product, which used a conical shape, could be viewed as possessing a spherical shape that appeared conical in profile.
  
• The court then re-analyzed the issue using the doctrine of equivalents. The district court, relying on Tronzo v. Biomet, Inc., 156 F.3d. 1154 (Fed. Cir. 1998), had held that under the "all elements rule," it could not find a conical shape equivalent to a spherical shape without reading the limitation out of the claim. The Federal Circuit disagreed. First, the "all elements rule" cannot be read to hold that the doctrine of equivalents is foreclosed whenever a claim limitation does not literally read on an element of the accused device, because that rule would swallow the doctrine of equivalents entirely. Then, observing that in Tronzo, the patentee's theory of equivalence was that any shape would be equivalent to the conical limitation (contrary to clear indications in the written description), the court distinguished DePuy's evidence. Its experts had identified shapes that would not have been equivalent, and presented particularized declarations demonstrating that a specific element of Medtronic's device was insubstantially different from the corresponding limitation. A reasonable jury could therefore find the devices equivalent.
  
• Another issue was a limitation requring that the screw head "pressed against the hollow spherically-shaped portion," and whether it was enough that the head rested against the edge of the equivalent receiver, or whether it must rest against the actual spherically-shaped portion equivalent. Looking to dependant claims in the patent, which specified screw heads that would be substantially equal to the radii of the receiver, the court concluded that the independent claim must be broad enough to read a device with components of unequal radii that pressed against each other. It further noted that there was no stated reason to exclude the edge of the receiver from the limitation, nor was there a stated reason to require a certain amount of contact, and the prosecution history provided no further guidance. Thus it adopted the broader reading of the limitation.
  
• With this broader interpretation of the "pressed against" limitation, the Federal Circuit rejected the district court's application of the function-way-result test, which had led it to find that because the Medtronic screw head merely pressed against the edge of the receiver, it did not do "substantially the same thing" as the patented device and hence the devices were not equivalent. Using the Federal Circuit's reading, the devices could be equivalent.
  
• Summary judgment finding no infringement was affirmed as to another class of screws, where the claim included a functional limitation that required an opening through which a screw could be inserted. Medtronic's product had a bore into which the screw fit, but the screw could not go through the opening; Depuy had argued the opening limitation was met by a snap ring, but the ring was located next to the bore, not opposite it, and therefore did not match the limitation requiring that there be an aperature opposite the bore through which the screw would fit. Thus, the functional restriction of the opening limitation was not met, and as a matter of law this group of screw models did not infringe.
  
• A final argument Medtronic raised was that a claim limitation requiring a "compressed member" should have been construed as a means-plus-function limitation, and under that reading none of its screw models would infringe. The Federal Circuit rejected that argument, first noting that the claim language did not include the term "means," and citing prior caselaw holding that this established a strong, albeit rebuttable, presumption that the limitation is not means-plus-function. Moreover, means-plus-function claims apply only to purely functional limitations, where the structure performing the function is not provided. Given that the limitation at issue did not use the term "means," and the claims and specification unmistakably established a reference to a particular structure, the Federal Circuit found the presumption was not rebutted, rejecting Medtronic's argument.
  
• An argument Medtronic advanced on cross-appeal, related to denial of a JMOL motion that lost profits were not available because the plaintiff was not an exclusive licensee for the entire period at issue, was reviewed by the Federal Circuit as a question of law, contrary to Depuy's assertion that the license rights involved a factual question. In so finding, the Federal Circuit reasoned that the underlying facts were not in dispute. The district court had allowed lost profits prior to the plaintiff becoming an exclusive licensee, because it was "closely tied" via a joint venture to the manufacturer. The Federal Circuit applied state law in reviewing the license agreement, and concluded there was an exclusive license during the relevant time period. It thus affirmed denial of JMOL on this issue.