dissenting.
Because I believe the facts in these cases weigh heavily against the application of collateral estoppel, I dissent. Put simply, in Nos. 91-1317 and 92-1244, Astee has had every opportunity to challenge the validity of the patents asserted against it in this litigation. It had a full and fair trial, and validity was further explored in detail on an interlocutory appeal to this court. Mendenhall v. Astec Indus., Inc., 887 F.2d 1094, 13 USPQ2d 1956 (Fed.Cir.1989) (table). The result was that we affirmed that Astee had failed to meet its burden of proving the patents invalid. Mendenhall has a final judgment that its patents are not invalid as asserted against Astee, and that is the law of this case.
As a “matter of sound judicial practice” a court will adhere to its prior decision and generally refuse to reopen what has been decided unless there are “exceptional circumstances” that compel a departure from this “law of the ease.” Central Soya Co. v. George A Hormel & Co., 723 F.2d 1573, 1580, 220 USPQ 490, 495 (Fed.Cir.1983). This “doctrine insures judicial efficiency and prevents endless litigation. Its elementary logic is matched by elementary fairness — a litigant given one good bite at the apple should not have [a] second.” Perkin-Elmer Corp. v. Computervision Corp., 732 F.2d 888, 900, 221 USPQ 669, 678 (Fed.Cir.1984) (citation omitted). Astee has had its bite at the apple.
The only “exceptional circumstance” relied upon by Astee is that it should be entitled to assert collateral estoppel against Mendenhall because of the result of Mendenhall v. Cedarapids, Inc., 5 F.3d 1557, 28 USPQ2d 1081 (Fed.Cir.1993), holding the patents invalid. Estoppel, however, is not appropriate in all cases where it might be interposed and its *1585use is left to the sound discretion of the court. Blonder-Tongue Labs., Inc. v. University of Illinois Foundation, 402 U.S. 313, 333, 91 S.Ct. 1434, 1445, 28 L.Ed.2d 788 (1971). “ ‘Claims of estoppel in patent cases [are] considered on a case by case basis, giving due weight to any factors which would point to an unfair or anomalous result from their allowance.’” Id. at 319, 91 S.Ct. at 1437-38 (quoting brief of the United States). It should only be applied when a court determines it is “just and equitable to allow the plea of estoppel in the case before it.” Id. at 334, 91 S.Ct. at 1445.
As explained by the Supreme Court, the primary reasons for the application of estop-pel in patent cases are economic. The “question is whether it is any longer tenable to afford a litigant more than one full and fair opportunity for judicial resolution of the same issue.” Id. at 328, 91 S.Ct. at 1442. The Court determined that the rule of Triplett v. Lowell, 297 U.S. 638, 56 S.Ct. 645, 80 L.Ed. 949 (1936), put an excessive financial burden on an alleged infringer if it were to pay the costs of a full defense in a suit brought subsequent to a patent being held invalid. There was also the opportunity for multiple relitigation by a patent holder to harass competitors, force settlements and unfairly attempt to expand its “monopoly.” And the costs in terms of judicial resources expended in multiple infringement suits were important in imposing collateral estoppel in a later suit brought by the patent holder for infringement of the same patent previously held invalid.
None of these reasons supporting collateral estoppel are present here, and its use serves no legitimate purpose. This is not a ease where a party is defending in a subsequent infringement litigation after a holding of invalidity. Astee itself has already had a full and fair opportunity for resolution of the validity issue. The ruling of invalidity in Cedarapids came after the final judgment on the merits of this case. Applying estoppel here would not save anything in the way of judicial resources. Of course, if Mendenhall attempted to bring a future suit, collateral estoppel would be entirely appropriate, but not here. The cows have left the barn, slamming the door now serves no purpose. The invocation of collateral estoppel in favor of Astee is not a “just and equitable” result.
In the Barber-Greene litigation, Nos. 91-1109 and 91-1131, the above considerations counsel against the application of estoppel against Mendenhall as well. Even more importantly, Barber-Greene waived any right it may have had to challenge validity, by collateral estoppel or otherwise, when it agreed to be bound by the result of the validity phase of the Astee litigation. Not only did Barber-Greene tell the district court, in seeking a stay of its ease, that it would be bound by the ruling on validity in Astee, but it also filed a stipulation that the validity and enforceability of Mendenhall’s patents were not at issue in their case and this stipulation was incorporated into the district court’s final order and judgment.
The agreement to be bound is clear and enforceable and precludes Barber-Greene from challenging the validity of the patents in this appeal. See Foster v. Hallco Manufacturing Co., 947 F.2d 469, 474, 20 USPQ2d 1241, 1245 (Fed.Cir.1991) (policies of preserving the finality of judgments and of encouraging settlements support the ruling that a consent judgment of patent validity will be given subsequent preclusive effect). In deferring to the ruling in Astee about the validity of the patents, Barber-Greene gained the benefit of the stay in the district court, appropriately granted in the interest of judicial economy and in accordance with the public interest in the orderly and expedient settlement of disputes. Barber-Greene is bound by its stipulation on validity and should not be allowed to escape by raising collateral estoppel at this stage of the game.