NOK, Inc. (NOK) appeals from the judgment of the United States District Court for the Eastern District of Michigan holding that U.S. Patent 3,498,621 is not invalid or unenforceable and is infringed. Dana Corp. v. NOK, Inc., 7 USPQ2d 1827 (S.D.Mich.1988). We reverse the district court’s validity determination and remand for further proceedings.
Background
The '621 patent, entitled “Valve Stem Seal,” issued to R.R. Wilson in 1970 and was assigned to Dana Corporation (Dana). Danа sued NOK for infringement of the ’621 patent. NOK’s defense was that the ’621 patent was unenforceable due to inequitable conduct before the United States Patent and Trademаrk Office and that it was invalid for failure to comply with the best mode requirement of 35 U.S.C. § 112 (1982).
In a separate action in the same court, Dana sued IPC Ltd. Partnership for infringement of thе ’621 patent. In that case the patent was similarly found not invalid and infringed. We reversed the validity holding of the district court,
Dana Corp. v. IPC Ltd. Partnership,
*507 ISSUE
Does the holding of invalidity of the ’621 patent in the IPC litigation collaterally es-top Dana from asserting in this litigation that that patent is valid?
OPINION
I
NOK cites
Blonder-Tongue Laboratories, Inc. v. University of Illinois Found.,
In
Blonder-Tongue,
the Supreme Court reversed the rule previously enunciated in
Triplett v. Lowell,
Nothing in
Blonder-Tongue
indicates that timing of the dеcision giving rise to estoppel is critical or that the plea of that defense cannot thereafter be timely made at any stage of the affected prоceedings. Thus, we see no reason for declining to permit estoppel to be raised in this case.
1
See Thompson-Hayward Chem. Co. v. Rohm and Haas Co.,
The Supreme Court explained in
Blonder-Tongue
that it was not suggesting “that a plea of estoppel by an infringement or royalty suit defendant must automatically be accepted.”
*508 Because the invalidity decision in the IPC litigation was issued during the briefing for the appeal in this litigation, NOK first raised estoppel in its reply brief. The parties addressed the issue at oral argument, during which Dana’s counsel asserted that collateral estoppel should not be applied against Dana to defeat its infringement claim against NOK based on invalidity of the ’621 patent. After oral argument, this court ordered the parties to file supplemental briefs on that issue. Dana was required to address “its position that collateral estoppel should not be applied to this case and the related questiоn of the propriety of this court, in the first instance, making that determination.”
In response to this order, Dana filed a supplemental brief arguing only that “Blonder-Tongue does not apply tо appeals.” As to whether a remand is necessary, Dana answered: “No.... There was not, and is not, any estoppel issue for the trial court.” Dana did allege, however, that “the NOK record differs materially from the findings of this court that led to the IPC reversal” and that “the differences between the NOK record and this court’s IPC findings lead to different results.”
“Res judicata
аnd collateral estop-pel are affirmative defenses that must be pleaded. Fed.Rule Civ.Proc. 8(c).”
Blonder-Tongue,
Even assuming that the
NOK
and
IPC
records differ materially, this alone will not defeat the application of collateral estoppel. The party opposing a plea of estoppel must establish that it did not have a full and fair opportunity to litigate; it must demonstrate that “without fault of his own the patentee was deprivеd of crucial evidence or witnesses in the first litigation.”
Because we hоld that the defense of collateral estoppel is applicable in this case in favor of NOK, we need not address NOK’s contentions of error by the district court with respect to the other grounds of invalidity and noninfringement.
II
NOK contends that the ’621 patent is unenforceable for inequitable conduct before the patent office. Bеcause we have concluded the ’621 patent is invalid, we need not address its unenforceability. However, the issue of inequitable conduct has relevance to NOK’s request for attorney fees. The district court considered the materiality aspect of inequitable conduct and concluded “that the [information and data] was not mаterial.” Thus, it was unnecessary for the court to consider the intent element of inequitable conduct.
See Kingsdown Medical Consultants, Ltd. v. Hollister, Inc.,
What was withheld from the Patent Office, but deemed not material by the district сourt, however, was delineated in IPC *509 as contributing significantly to our holding that the best mode was not disclosed in the ’621 patent. The materiality of the withheld material is evident from the IPC decision.
Wе remand this case to the district court to reconsider its inequitable conduct determination. On remand, the district court must determine whether the conduct of Dana amounts to inequitable conduct.
See Kingsdown,
COSTS
Costs to NOK.
REVERSED AND REMANDED.
Notes
. Dana’s contention that
Thompson-Hayward Chem. Co. v. Rohm and Haas Co.,
. In fact, such a showing would be difficult in this case. The evidence Dana allеges to be different in the NOK case appears to have always been within its control and readily available at the time of the IPC trial. For example, Dana pоints to a report of its employee, Mr. Wilson, the inventor of the '621 patent, and an internal transmittal letter explaining that the patent application meets with Mr. Wilson’s approval. Further, the same counsel appears to have represented Dana in the trial of both cases.
