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Patentee’s Statements During Reexamination Making Explicit the Meaning of a Claim Term Already Implicit in the Patent Did Not Create Estoppel

January 07, 2008

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Last Month at the Federal Circuit - February 2008

Judges: Bryson (author), Friedman, Keeley (Chief District Judge sitting by designation)

[Appealed from: D. Del., Judge Robinson]

In Cordis Corp. v. Medtronic AVE, Inc., Nos. 06-1393, -1394, -1395, -1396, -1415, -1416 (Fed. Cir. Jan. 7, 2008), the Federal Circuit affirmed the district court’s denials of both Medtronic AVE, Inc.’s (“AVE”) and codefendants Boston Scientific’s and Boston Scientific Scimed, Inc.’s (collectively “BSC”) motions for a new trial and JMOL, reversed the district court’s invalidation of a claim that the jury found to have been infringed by BSC, and remanded.

U.S. Patent Nos. 4,739,762 (“the ’762 patent”) and 5,195,984 (“the ’984 patent”) relate to vascular stents used to treat coronary artery disease. The ’762 patent discloses a stent that can be mounted on an angioplasty balloon and delivered intraluminally (i.e., through the vascular system) to the target location. Once this stent reaches the location, the balloon and stent are expanded and the stent props open a constriction in the blood vessel. Claim 23 of the ’762 patent covers an expandable intraluminal vascular stent comprising “a . . . tubular member having . . . a wall surface . . . , the wall surface having a substantially uniform thickness and a plurality of slots formed therein.” In addition, claim 23 requires the wall surface to be a “smooth surface.” The ’984 patent discloses a flexible stent manufactured by joining tubular members, such as those disclosed in the ’762 patent, by a connector to provide the flexibility to negotiate curves in body passageways such as the vascular system.

In separate cases in the District of Delaware, Cordis Corporation (“Cordis”) alleged that three AVE stents infringed both the ’762 and the ’984 patents, and that BSC’s NIR stent infringed claim 23 of the ’762 patent. After these litigations began, Cordis sought reexamination of the ’762 patent. During reexamination, Cordis narrowed the scope of the ’762 patent by distinguishing the claimed invention from a prior art patent. Cordis also cancelled independent claim 13 and incorporated all the limitations from that claim into claim 23, previously dependent from claim 13. In the remarks accompanying the amendment, Cordis distinguished the claimed invention from a prior art patent based on the “wall surface,” “smooth surface,” and “substantially uniform thickness” limitations.

Cordis obtained separate jury verdicts of infringement against AVE and BSC. AVE and BSC each filed a motion for a new trial and for JMOL of noninfringement. Both appealed the district court’s denial of those motions and the appeals were consolidated. In addition, Cordis cross-appealed the district court’s invalidation of a claim found to have been infringed by BSC.

On appeal, AVE argued it was entitled to JMOL of noninfringement of the ’762 patent because its stents do not have walls of “substantially uniform thickness,” as recited by claim 23. AVE’s stent is formed by a group of rings made of metal strands with circular cross-sections. The rings are bent into a sinusoidal shape along their circumference. Multiple rings are welded together to make the stent. The walls of the stent thus consist of straight sections, called struts, that connect the rings as well as curved sections, called crowns, between the struts. Regarding the “substantially uniform thickness” claim limitation, AVE acknowledged that the cross-section of the metal strands in the strut sections was uniform. AVE nevertheless argued that the thickness of the stent wall should not be measured by the cross-section of the metal but rather by the length of the chords that cross the curved tip of the crowns, as measured along a line drawn from the center of the stent perpendicular to the wall. The Federal Circuit disagreed with AVE’s measuring technique, holding that “a stent with round crowns can have substantially uniform thickness as long as the round crowns have substantially the same diameter.” Slip op. at 9.

In addition, AVE argued that the district court erred in leaving the issue of how to measure thickness of the stent wall to the jury. According to AVE, the methodology of measurement should have been deemed an issue of law. The Federal Circuit explained that even if the methodology issue had been an issue of law, it rejected the idea that the district court should have adopted AVE’s methodology. For that reason, AVE could not have been prejudiced by the district court’s treatment of the methodology as an issue of fact.

AVE also argued that it was entitled to JMOL of noninfringement of the ’984 patent because its stents did not infringe the “flexibly connect” limitation. The Federal Circuit stated that neither the claim language nor the district court’s claim construction required the connector members themselves to be flexible. Rather, the claim language required the connector members to “flexibly connect adjacent tubular members,” and the district court construed that phrase to require the connector members to “provide flexibility.” Even if the connector members themselves were not flexible, the Court concluded that Cordis’s evidence was sufficient to demonstrate that the connector members nevertheless provide flexibility to AVE’s accused stents.

AVE also argued it was entitled to a new trial on several grounds. First, AVE challenged the district court’s decision to prevent AVE and its experts from telling the jury that AVE’s methodology of measuring stent wall thickness was endorsed by the Federal Circuit in a prior appeal. The Federal Circuit determined, however, that it had not in fact agreed with the methodology in the prior appeal and, thus, the district court properly barred AVE from telling the jury that the earlier panel supported AVE’s methodology.

Second, AVE argued it was prejudiced by the district court’s exclusion of evidence demonstrating clinical advantages of AVE’s stents. The Federal Circuit disagreed, stating that the excluded evidence was irrelevant to the question of infringement and that such evidence was introduced through other sources.

Finally, AVE argued that the jury instruction regarding obviousness conflicted with KSR International v. Teleflex Inc., 127 S. Ct. 1727 (2007), because the jury instruction, which AVE actually proposed, was based on pre-KSR law. The Federal Circuit explained that KSR did not represent a significant change in the law and that “even in the case of a change in the law, the Supreme Court has held that the plain error standard applies to a jury instruction to which no objection was made.” Slip op. at 19. Thus, the Court determined that AVE had not “remotely demonstrated that it is entitled to a new trial on obviousness.” Id. at 20.

Turning next to BSC’s appeal, the Federal Circuit addressed BSC’s argument that the term “slots” in claim 23 of the ’762 patent should have been construed to cover only “complete” slots (slots that are bounded on all sides), and the district court erred by construing the term to also include “half” slots (slots that are not completely bounded). The Federal Circuit disagreed, finding that the specification’s reference to “half-slots” did not “foreclose the generic term ‘slots’ from being used to refer to both half slots and complete slots.” Id. at 22. BSC also argued that the district court’s construction of “slots” was incorrect because, under that construction, the claim would cover inoperable embodiments. The Court again disagreed, stating that a construction is only “viewed with extreme skepticism” when that construction renders all embodiments inoperable as opposed to rendering some embodiments inoperable. Id. at 23.

Second, BSC argued that no reasonable jury could have found that the NIR stent infringed the “wall surface” and “smooth surface” claim limitations of claim 23 of the ’762 patent. The district court defined the “wall surface” limitation to require that the “outer surface of the tubular member must be disposed in a common cylindrical plane.” The jury returned a general verdict of infringement under the DOE. BSC advocated a narrow reading of “wall surface” such that the outer surface had to be a perfect cylinder. Because the NIR stent had weld points on the outer surface, BSC argued it could not literally infringe. The Federal Circuit found that definition too narrow and held that, even without applying the DOE, a jury could reasonably conclude that the presence of weld spots on the stent’s surface does not sufficiently alter the cylindrical character of the outer surface to preclude a finding of literal infringement.

BSC also argued it was entitled to a new trial on infringement because the district court should have ruled that prosecution history estoppel barred equivalents of the “wall surface” limitation. The Court disagreed, explaining that prosecution history estoppel applies when a party makes clear and unmistakable statements disavowing subject matter such that “a competitor would reasonably believe that the applicant had surrendered the relevant subject matter.” Id. at 28 (citation omitted). Here, the Court determined that Cordis made no disavowing statements during reexamination when it simply made explicit the meaning of the term “wall surface” that was already implicit in the ’762 patent. The Court reasoned that “there is no reason to treat Cordis’s definitional explanation in the prosecution history as having the effect of surrendering all equivalents that would otherwise be available under the patent.” Id. at 29. Thus, prosecution history estoppel did not apply.

As to BSC’s motion for JMOL of noninfringement with respect to the “smooth surface” limitation, the district court defined “smooth surface” to require that the “outside of the wall surface of the unexpanded tubular member [have] a continuously even surface, without roughness, points, bumps or ridges, especially to the touch.” Id. at 24-25. The Federal Circuit determined that the district court’s definition was unnecessarily restrictive. Based on the prosecution history, the Court would have defined “smooth surface” functionally to mean “smooth enough to be capable of intraluminal delivery.” Id. at 33. Thus, the Court found that it was unnecessary to look to the DOE as the basis for upholding the jury’s finding of infringement, because a reasonable jury under the Court’s broader definition would have found the NIR stent literally infringed. The district court thus properly denied BSC’s motion for JMOL of noninfringement with respect to the “smooth surface” limitation. The Court did note that BSC may be entitled to another trial based on obviousness in light of this broader definition of “smooth surface” but left that matter to the district court on remand.

Third, BSC argued that the wall surface of its NIR stent does not exhibit “substantially uniform thickness” and that the district court erred in not granting JMOL of noninfringement. The district court followed the Federal Circuit’s guidance in a prior appeal that “substantially uniform thickness” means “[t]he wall of a tubular member must be of largely or approximately uniform thickness.” BSC argued that the weld spots produce variations in thickness of the stent’s walls and, therefore, the wall cannot be of “substantially uniform thickness.” The Court rejected this argument, finding that the method to measure wall thickness was a question of fact. Thus, the jury reasonably concluded, based on expert testimony by Cordis’s expert, that the proper method to measure wall thickness was to measure the thickness of the stent struts.

BSC also argued that the district court instruction saying, “[l]et me remind you that the ‘wall surface’ limitation is not in dispute in this case” was prejudicial because it suggested that the “wall surface” limitation was literally infringed. The Court rejected this argument because the instruction said nothing about infringement of the “wall surface” limitation and, thus, the instruction was appropriate.

Finally, BSC challenged two evidentiary rulings regarding the issue of obviousness. Because claim 23 is an apparatus claim rather than a method claim, BSC sought to introduce evidence regarding several of the ’762 patent’s method claims in an effort to point out the differences between those method claims and claim 23 as well as counter Cordis’s evidence of commercial success. The district court excluded such evidence under Fed. R. Evid. 403. The Federal Circuit determined that because claim 23 was the only claim asserted in that trial, the district court properly excluded evidence of other nonasserted claims.

BSC also sought to introduce evidence about Cordis’s interest in acquiring rights to the NIR stent from BSC. BSC hoped to counter evidence of Cordis’s commercial success by demonstrating any success was due to the stent’s flexibility, a feature not covered by claim 23. The district court again excluded such evidence under Fed. R. Evid. 403. The Federal Circuit determined that the district court had properly focused the jury’s attention on the prior art and the claimed invention instead of the accused device.

In a cross-appeal, Cordis challenged the district court’s invalidation of claim 44 of the ’762 patent under 35 U.S.C. § 305, providing “[n]o proposed amended or new claim enlarging the scope of a claim of the patent will be permitted in a reexamination proceeding.” During reexamination, Cordis added claims 44 to 59 in response to a 1998 Office Action. The district court decided claim 44 was invalid because it was not added to either “(1) distinguish the invention as claimed from the prior art” or “(2) in response to a decision adverse to the patentability of a claim of a patent,” as required by § 305. The district court determined that claim 44 was “added solely to cover competitors’ stents, and not for a permissible reason under § 305.” The Court determined that the district court misinterpreted § 305, stating that the addition of claims 44 to 59 fell under option two because they were intended to distinguish the invention in response to the 1998 Office Action. Because these claims did not “enlarge the scope of the original claims,” the claims satisfied the validity requirements of § 305. Slip op. at 43.