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February 5, 2007

Unenabled Alternative

Medtronic sued BrainLAB for infringing four patents claiming "image-guided surgery products that enable the precise localization of surgical instruments used during surgery." In its own surgical operation, BrainLAB removed a jury-implanted infringement tumor, using careful claim construction, narrowing to non-infringement, that the judge approved as a matter of law. Medtronic's appeal was to no avail.

Medtronic v. BrainLAB (CAFC 06-1289)

The asserted patents were 4,722,056, 5,383,454, 5,389,101, and 5,603,318.

The one lesson from this case is to enable alternative embodiments, or they are not likely to be covered in litigation claim construction. As the appeals court put it: "a minimal dropping of an unenabled reference to an undeveloped system does not support a claim to it."

With regard to claim construction, Medtronic asserts that the court incorrectly construed the following claim limitations: (1) "reference means" of claim 14 of the '454 patent, (2) "establishing the spatial relationship" of claim 1 of the '056 patent, and (3) "workspace coordinate framework" of claim 1 of the Heilbrun patents.

Medtronic wanted "reference means" construed broadly, in terms of "sensors" or "receivers." But all the specification pointed to were microphones, i.e., sound detection.

The court construed the first disputed term "reference means" as "an array of microphones," rejecting Medtronic's proposed construction of "one or more sensor(s) or receiver(s)." As the court correctly noted, the specification consistently describes the use of "arrays" to detect sound emissions transmitted from emitters located on the base ring (or head) and the surgical probe as part of the process of determining the position of the probe. '454 patent, col.5 ll.30-35, col.6 ll.8-35, col.7 ll.2-35 & Figs. 3A-3B. Indeed, the specification describes that key component of the invention in terms of a "microphone array" or "microphones of the array," and does not describe it in terms of "sensors" or "receivers," as Medtronic contends. The court also rejected Medtronic's claim differentiation argument.

For "establishing the spatial relationship," Medtronic wanted an optical tracking system included within the claim scope. An optical tracking system had been mentioned in the disclosure as an alternative embodiment. But it had been a single mention, and, crucially, lack of enablement was telling.

The relevant issue on appeal with respect to the second disputed term, "establishing the spatial relationship," is whether the district court properly excluded "the use of an optical reference system" from its construction. Claim Construction Op. at 7. Referencing the specification, the district court noted that the specification describes "an acoustic or ultrasonic range finding system" as well as "an electromagnetic position and orientation system" to track the movement of an object. Id. at 6 (citing '056 patent, col.6 l.48-col.11 l.18, col.11 l.18-col.12 l.32). The court further noted that although the specification mentions the use of an optical system, the statements were "too general in nature" to support Medtronic's broad proposed construction. Id.

Similar to the '454 patent, the specification of the '056 patent discloses that the spatial relationship is established by using an acoustic tracking system or an "ultrasonic range finder or reference system" that uses spark gaps that emit "energy in the form of sound pulses which are received by (at least) three microphones." Id. col.6 ll.48-58. The specification also describes in detail the use of "an electromagnetic position and orientation system." Id. col.11 ll.18-20. Medtronic's argument for inclusion of an optical tracking system is largely premised on a single statement that appears in the specification, i.e., that "[a]n optical system can be used as an alternative to the acoustic system described earlier." Id. col.12 ll.33-34.

We agree with the district court that this passing reference to an optical tracking system fails to support an interpretation broader than that adopted by the court. A claim is to be construed in light of the written description that supports it. Phillips v. AWH Corp., 415 F.3d 1303, 1315 (Fed. Cir. 2005) (en banc). And it is true that the minimal one sentence reference to an optical tracking system is a mention of an optical tracking system. However, the remainder of the specification describes acoustic systems. There is no enabling description of how to make and use an optical tracking system, and claims are best construed to preserve their validity. Tate Access Floors, Inc. v. Interface Architectural, 279 F.3d 1357, 1369 (Fed. Cir. 2002); see also Modine Mfg. Co. v. U.S. Int'l Trade Comm'n, 75 F.3d 1545, 1557 (Fed. Cir. 1996) (overruled on other grounds); Athletic Alternatives, Inc. v. Prince Mfg., Inc., 73 F.3d 1573, 1581 (Fed. Cir. 1996). Because this case is one in which ambiguity as to the scope of the claim language can be "resolved in a manner that would preserve the patent's validity," Phillips, 415 F.3d at 1327, that principle can properly be applied here. Moreover, the inventor himself stated, in answer to a series of questions regarding whether an optical tracking unit was available to him at the time of his invention of the acoustic system that "[w]e weren't aware of any commercial optical tracking system that was available" and "[i]t seemed at the time that this would be an obvious development, that it would be coming in time. It was just that at this time that we were writing this, that such a system wasn't available to us." J.A. at 6562 (emphasis added). Thus, rather than being a disclosure of an optical system sufficient to support an interpretation of a claim as including an optical system, it was merely "an attempt to preempt the future before it has arrived." Fiers v. Revel, 984 F.2d 1164, 1171 (Fed. Cir. 1993). Such a minimal dropping of an unenabled reference to an undeveloped system does not support a claim to it.

The term "workspace coordinate framework" was deemed a static coordinate system, based upon the spec.

With regard to the last disputed claim term, the district court construed "workspace coordinate framework," which appears in claim 1 of the Heilbrun patents, as "a static or immovable coordinate system centered in the workspace that must be re-established if one or more of the cameras are moved." Claim Construction Op. at 25. The court noted that the specification explains that the workspace coordinate framework is a three-dimensional reference system that is "computed from two digitized 2-dimensional images of the fiducial structure 220 provided respectively by cameras 200, 202, plus the known location parameters of fiducial points on fiducial structure 220." Id. at 24-25 (citing Heilbrun patents, col.6 ll.32-37). The court further noted that, based on the specification, once the framework is established, the fiducial structure can be removed and the instrument can be tracked "so long as the cameras remain fixed in their positions relative to the workspace." Id. at 25. Importantly, the specification discloses that "[i]f it is desired to select new locations for making the image pairs . . . all that need be done is to reposition the fiducial structure in the workspace to make a new pair of calibration images." Id.; Heilbrun patents, col.13 ll.40-44. That statement supports the district court's conclusion that the coordinate framework is a static one that must be reestablished if the cameras move.

Prosecution estoppel precluded application of doctrine of equivalents; narrowed amended claims surrendered equivalency scope that Medtronic needed.

Medtronic was precluded by prosecution history estoppel from asserting infringement of the '454 patent under the doctrine of equivalents. The district court noted that the examiner rejected all twenty-five of the original claims that were included in the '454 patent application as anticipated under 35 U.S.C. § 102 and not in compliance with paragraphs 1 and 2 of § 112. In response, Bucholz made several statements during prosecution in order to overcome the rejections. Bucholz also amended his claim to include the "reference means" and added an additional step to the claim. Medtronic asserts that Bucholz's statements and the amendment fail to establish a clear disavowal or surrender of subject matter. We disagree. Based on the prosecution history, we agree with the district court's reasoning and conclude that Bucholz clearly narrowed the scope of his invention in exchange for the allowance of his claims, thus surrendering subject matter that encompasses what Medtronic now claims to be equivalent. We therefore agree with the district court that Medtronic was precluded from arguing that the passive optical tracking system used in BrainLab's products is an equivalent of the claimed reference means.

Posted by Patent Hawk at February 5, 2007 1:37 PM | Claim Construction


It is interesting that the very same rationales adopted by the CAFC could be applied to the Saffran patent claims in the litigation with Boston Scientific and J & J to void the recent district court/jury verdict. Saffran's one word reference to stent drug coating is "a minimal dropping of an unenabled reference to an undeveloped system does not support a claim to it."

Posted by: JFB at February 26, 2008 7:30 AM