Michel, Circuit Judge, Archer, Senior Circuit Judge, and Schall, Circuit Judge.
The opinion of the court was delivered by: Michel, Circuit Judge
Appealed from: U.S. District Court for the Southern District of Texas judge Vanessa D. Gilmore
Defendants, Cat Contracting, Inc. ("CAT"), Michigan Sewer Construction ("MSC"), Kanal Sanierung Hans Mueller GmbH & Co. KG ("KM"), and Inliner U.S.A. ("Inliner") (collectively, "Defendants") appeal the judgment of the United States District Court for the Southern District of Texas in Insituform Technologies, Inc. v. Cat Contracting, Inc., CA No. H-90-1690 (Dec. 31, 1996) (hereinafter, "Insituform II"), holding Inliner's Processes 1 and 2 each infringes claim 1 of United States Patent No. 4,336,012 (the "'012 patent") under the doctrine of equivalents and enjoining Defendants from practicing either Process 1 or 2. Because we hold that Inliner's Process 1 was shown to infringe the '012 patent, but Inliner's Process 2 was not shown to infringe, we affirm-in-part, and reverse-in-part.
The '012 patent is directed towards a process for lining pipelines and passageways, particularly sewers, which may suffer from leaks. Using the patented method, damaged underground pipelines and passageways can be repaired without removing them from the ground. Claim 1 covers a method for the impregnation of a flexible tube liner prior to installing the liner in a damaged pipeline. The liner has an outer layer of impermeable film and an inner, resin-absorbent, felt layer. The claimed method involves applying a vacuum to the inside of the liner by cutting a window in the outer impermeable film layer, applying a cup to the outside of the window, and connecting the other end of the cup to a vacuum source using a flexible hose. As each section of the liner has its resin-absorbent material impregnated, the cup is moved downstream and the previous window is sealed. The process is repeated for respective lengths of liner until the entire liner has been impregnated. The resin-impregnated liner is then inserted into a damaged pipe. The method of installation in the pipe is not at issue here.
Inliner's Process 1, the "multiple cup process," uses four to six cups to draw a vacuum from a corresponding number of windows in the liner. When the cup closest to the advancing resin is removed and the window that was beneath it is sealed, the remaining downstream cups continue to draw a vacuum in the liner. See Insituform Gulf South, Inc. v. CAT Contracting, Inc., 99 F.3d 1098, 1104-05, 40 USPQ2d 1602, 1607 (Fed. Cir. 1997) (hereafter, "Insituform I"). Interruption of the vacuum during the impregnation process is thereby avoided or diminished by the use of the multiple cups. Inliner's Process 2, the "multiple needle process," replaces multiple cups with multiple metal tubes or needles. The needles are inserted through all of the layers of the liner rather than merely placed over holes in the outer layer, and they provide a continuous vacuum from inside the liner rather than through the felt. See id. *fn1
In 1990, Insituform sued Defendants for infringement of the '012 patent and of United States Patent No. 4,009,063 (the "'063 patent"), *fn2 both claiming methods invented by Eric Wood and owned by Insituform Technologies, Inc. Liability and damages were bifurcated, and damages are not at issue here. In 1991, a jury returned a verdict that the '012 patent was infringed by both Processes 1 and 2 and was not invalid. The district Judge granted Inliner's motion for JNOV with respect to literal infringement of both processes, and ordered a new trial with respect to infringement under the doctrine of equivalents. In 1995, at the retrial the court found equivalent infringement of claim 1 by both processes. On appeal, this court affirmed the order for JNOV with respect to literal infringement but vacated the district court's determination of equivalent infringement as based on an erroneous claim construction and remanded the case for re-determination of equivalent infringement based on the correct claim construction. See Insituform I, 99 F.3d at 1109, 40 USPQ2d at 1610.
Method claim 1, the only claim at issue, is reproduced below. *fn3 For background in the technology and in the patent in suit, the reader is directed to Insituform I, 99 F.3d 1098, 40 USPQ2d 1602. In Insituform I, this court interpreted certain limitations of claim 1. Specifically, we held that the literal scope of claim 1 is limited to "a process using only one vacuum cup which inherently creates a discontinuous vacuum." Insituform I, 99 F.3d at 1106, 40 USPQ2d at 1608. Under the correct claim construction, we affirmed the district court's JNOV of no literal infringement because the accused Inliner methods use multiple cups or needles. See id. at 1107, 40 USPQ2d at 1608. We also concluded that the doctrine of prosecution history estoppel did not preclude Insituform from asserting that its right to exclude extends broadly enough to cover either Process 1 or Process 2, but we did not affirm the district court's finding of infringement under the doctrine of equivalents because it was based on an incorrect claim construction. See id. at 1109, 40 USPQ2d at 1610. We therefore vacated the determination of infringement by Processes 1 and 2 under the doctrine of equivalents and remanded the case for the district court to re-determine equivalent infringement applying the correct claim construction. See id.
On remand the court determined that both Inliner's Processes 1 and 2 infringed claim 1 of the '012 patent under the doctrine of equivalents. Inliner timely appealed to this court, and the appeal was submitted for our decision following oral argument on July 8, 1998. We have jurisdiction over this appeal pursuant to 28 U.S.C. § 1295(a)(1) (1994).
I. Prosecution History Estoppel
Although we held in Insituform I that "the prosecution history does not estop Insituform from asserting that the right to exclude extends broadly enough to cover either Process 1 or Process 2," Insituform I, 99 F.3d at 1109, 40 USPQ2d at 1610, Defendants now argue that the district court erred in its determination on remand that "[t]here is nothing in the file history of the '012 patent or the prior art which prevents claim 1 from covering Defendants' processes," Insituform, slip op. at 20 (Dec. 31, 1996). [BB 38-39] According to Defendants, however, the Supreme Court's Warner-Jenkinson decision, issued after our remand in Insituform I, further limited the doctrine of equivalents so that it cannot apply in this case. See Warner-Jenkinson Co. v. Hilton-Davis Chem. Co., 520 U.S. 17, ----, 117 S. Ct. 1040, 1051, 41 USPQ2d 1865, 1873 (1997) (holding that where no explanation is given for an amendment made during prosecution of a patent, a presumption is to be applied against the patentee that the amendment was made for purposes of patentability). Inliner asserts that when Insituform amended claim 1 in response to a 35 U.S.C. § 103 rejection of application claims 1-6 based on United States Patent No. 4,182,262 to Everson ("Everson"), Insituform necessarily gave up coverage of any process in which the vacuum was created at multiple vacuum sources because it provided no explanation for such a narrowing amendment.
As we discussed in Insituform I, however, Everson discloses "both the use of a continuous vacuum and the creation of that vacuum from only a single vacuum source at the far end of the tube opposite the resin source." Insituform I, 99 F.3d at 1108, 40 USPQ2d at 1609. Everson discloses nothing about multiple vacuum sources or their placement on the liner close to the resin front. In its response to the PTO rejection, Insituform canceled application claim 1 and filed a new, narrower claim in its place. The new claim, which became patent claim 1, incorporated each of canceled claims 1, 2, 3, and 4, but otherwise added no new limitations. In its remarks to the PTO, Insituform specifically noted that:
Everson's method is ineffective when dealing with long lengths of tube because that method requires an exceedingly large suction compressor. Applicant's method solves the problem of impregnating long lengths of tubing by forming a window in the tube's impermeable ...