Opinion ID: 783155
Heading Depth: 1
Heading Rank: 3

Heading: Substantially Uniform Thickness

Text: 32 Cordis also challenges the district court's construction of the substantially uniform thickness limitation and the court's related ruling on prosecution history estoppel. We agree with Cordis that the court's claim construction was unduly narrow and that the court's estoppel ruling was erroneous. Accordingly, we reverse the court's order granting JMOL of noninfringement under the doctrine of equivalents and its grant of a conditional new trial on literal infringement as to that limitation. 33  The district court construed the substantially uniform thickness limitation to require that the thickness of the stent's wall surface not vary by 0.001 inch or more. Cordis contends that the district court erred by imposing the numerical restriction of 0.001 inch with respect to that limitation. 34 The patents do not set out any numerical standard by which to determine whether the thickness of the wall surface is substantially uniform. The term substantially, as used in this context, denotes approximation. See Epcon Gas Sys., Inc. v. Bauer Compressors, Inc., 279 F.3d 1022, 1031 (Fed.Cir.2002). Thus, the walls must be of largely or approximately uniform thickness. Moreover, the written descriptions of the two patents state only that the expansion of the tubular member is uniform along the length of tubular member 71 in part because of the uniform thickness of the wall surface, specifically pointing to the same uniform thickness of the connecting members 77, the elongate members 75, and members 78 and 79. '762 patent, col. 7, ll. 21-33; '984 patent, col. 6, ll. 47-54. Accordingly, the substantially uniform limitation also requires that the thickness of the wall surface be sufficiently uniform along its length and between members to allow uniform expansion of the stent. The question presented here is whether there is anything in the prosecution history of either patent that justifies giving the substantially uniform thickness limitation an even narrower construction. 35 In its discussion of the Ersek patent during reexamination of the '762 patent, Cordis argued that, according to the Antonsson affidavit, the Ersek device is not smooth and that the wall thickness [of an Ersek model] `varied at different points' and `ranged from a minimum thickness of 0.0035 inches to a maximum thickness of 0.0045 inches.' Cordis noted that the Antonsson affidavit addresses a model of an Ersek device in its expanded configuration, but that the thickness of the Ersek device is not substantially uniform in either its unexpanded or expanded configuration. Based on those statements, the district court construed the substantially uniform thickness limitation to require variations in wall surface thickness of less than 0.001 inch. 36 The commentary on Dr. Antonsson's measurement of a model, however, does not constitute a clear and unmistakable disclaimer, see Omega Eng'g, 334 F.3d at ___, slip. op. at 17, excluding stents that vary in thickness by 0.001 inch or more. Cordis did not suggest that the variation of 0.001 inch was the basis for distinguishing its invention from Ersek or that Cordis's claimed stents vary by less than 0.001 inch in thickness. Rather, Cordis's basis for distinguishing Ersek appears to have been that Ersek's walls were at least twice as thick at the intersections of strands as along the strands themselves. The alleged disclaimer based on Dr. Antonsson's measurements in the reexamination proceedings was at best ambiguous. See IMS Tech., Inc. v. Haas Automation, Inc., 206 F.3d 1422, 1439 (Fed.Cir.2000) (In light of the ambiguity of the patentee's statements and the subject matter actually disclosed in the references, we cannot say that the patentee clearly disavowed coverage of [the contested subject matter].). 37 In addressing Ersek, Cordis focused on the double thickness of the bridge portions of Ersek's walls. For example, in its response to the examiner's reexamination rejection of claims in light of Ersek, Cordis stated: 38 As shown ... in Ersek Figure 5 ... the wall of [the Ersek device] is of varying thickness because the strands of the sleeve have twisted out of the plane of the starting material. Moreover, the bonds or bridges at the junctions of the strands protrude inwardly and outwardly of the plane of the starting material, and as a result the Ersek sleeve 16 has a non-uniform wall of varying thickness. 39 Since the bonds or bridges extend generally radially outwardly of the sleeve 16, the sleeve has 100% variance in thickness as compared to the thickness of the starting material in the areas of the bonds or bridges. 40 Figure 5 of the Ersek patent is shown herein: 41 NOTE: OPINION CONTAINING TABLE OR OTHER DATA THAT IS NOT VIEWABLE 42 Cordis reiterated its contention that Ersek did not have a wall surface with a substantially uniform thickness in that submission: 43 Clearly, the Ersek sleeve cannot be fairly said to have a wall surface with a substantially uniform thickness. The expanded metal Ersek sleeve has bridge portions that are several times as thick as the strands.... The strands extending between the bridge portions are twisted to have inwardly and outwardly projecting edges. This irregular and variable configuration is rough and is the antithesis of substantially uniform thickness. The use of the term substantially uniform does not exclude some variations in dimension between the inner and outer surfaces of the wall. Even so, it is clear that Ersek's rough and irregular wall does not have substantially uniform thickness. Antonsson Affidavit, paragraph 10. 44 At Cordis's request, Dr. George Andros submitted a declaration to the PTO as a part of the reexamination of the '762 patent. Dr. Andros stated that [t]he Ersek fixation sleeve does not have a substantially uniform wall thickness, nor is it thin walled. The expanded metal sleeve is twice as thick in some areas as in others, and the thickness of the wall varies throughout. Cordis thus focused on the double thickness of the bridge portions of the Ersek device, not on Dr. Antonsson's assertion that the thickness of the Ersek device varied by up to 0.001 inch along the strands. 45 Based on our review of the prosecution history, we conclude that a reasonable reading of the patentee's statements would not lead one to conclude that variations greater than 0.001 inch fall outside the scope of the '762 patent. Because there is no clear and unmistakable disclaimer of any variation in thickness of 0.001 inch or more, the district court erred in imposing that numerical restriction on the substantially uniform thickness limitation. The discussion of the Ersek patent does, however, support the conclusion that the owner of the '762 patent disclaimed coverage of any device with a variation of at least 100 percent. In any event, quite apart from any disclaimer, a wall that varies in thickness by as much as 100 percent cannot be said to be of substantially uniform thickness either literally or by equivalents. B 46 AVE contends that, under either party's construction, its stents have a variable thickness because they have a round or ellipto-rectangular cross-section and thus do not infringe because the cross-sectional thickness of its stent walls varies by more than 100 percent. We disagree and conclude that a stent formed from struts with circular or ellipto-rectangular cross-sections can have a wall of substantially uniform thickness. 47 First, both AVE's and Cordis's experts agreed that persons of ordinary skill in the art equate thickness with diameter in the case of round struts. Second, according to the patents' claims, it is the wall surface that needs to have a uniform thickness, and the full circumference of the round strut is not involved in making up the wall surface. The district court described the wall surface by stating that [t]he outer surface of the tubular member must be disposed in a common cylindrical plane. That common cylindrical plane is formed by an imaginary circle that intersects with the outermost point of each round strut. The thickness of the wall is equal to the diameter of each round strut, i.e., the distance between the outer point that intersects the wall surface and the corresponding inner point that intersects a similar imaginary cylindrical surface on the inside of the tubular member. Thus, a stent with round struts can have a substantially uniform thickness as long as the round struts have substantially the same diameter. 48 We recognize that the '762 patent specifically references struts with a rectangular or square cross-section, '762 patent, col. 7, ll. 34-41, and that the '984 patent states that the cross-section of the struts may be square, rectangular, or other, '984 patent, col. 6, ll. 58-63. That description, however, does not exclude circular or ellipto-rectangular struts, which would also facilitate uniform expansion of the stents. C 49 The court concluded that allowing equivalents for the substantially uniform thickness limitation would vitiate the 0.001 inch variation requirement adopted by the court. Because we have rejected the 0.001 inch variation requirement, we reject that ground of the district court's doctrine of equivalents ruling. 50 AVE argues on appeal that the citation to the Antonsson affidavit during reexamination of the '762 patent created an argument-based estoppel. We reject AVE's argument to preclude infringement of the limitation through an equivalent. To invoke argument-based estoppel, the prosecution history must evince a clear and unmistakable surrender of subject matter. Litton Sys., Inc. v. Honeywell, Inc., 140 F.3d 1449, 1458 (Fed.Cir.1998). Just as the Antonsson affidavit failed to serve as a clear and unmistakable disclaimer in the claim construction analysis, it also fails to serve as a clear and unmistakable surrender of anything greater than 0.001 inch to bar coverage through the doctrine of equivalents. We have noted that the prosecution disclaimer standard is the same standard applicable, in the context of doctrine of equivalents, to the doctrine of argument-based estoppel ... and that our precedent has recognized a relation between the doctrines of argument-based estoppel and prosecution disclaimer. Omega Eng'g, 334 F.3d at 1326, slip op. at 17 n. 1. 51