concurring:
I concur with the result of the panel’s decision. I write separately to differ with the panel in its decision to review the judgment of noninfringement rather than that of invalidity. The case before us illustrates why, in an appropriate case, we should review an invalidity judgment first, and, if we affirm, then vacate or simply not rule on the infringement issue.
Both parties, including amici, ask that we review our “policy” stated in Vieau v. Japax, Inc., 823 F.2d 1510, 1517, 3 USPQ2d 1094, 1100 (Fed.Cir.1987) that, when affirming a district court judgment on non-infringement, we vacate the district court’s invalidity conclusion. In several recent cases in which a patent has been found invalid and not infringed, this court has affirmed the holding of noninfringement and vacated the holding of invalidity. E.g., Wilson Sporting Goods Co. v. David Geoffrey & Assoc., 904 F.2d 677, 686, 14 USPQ2d 1942, 1950 (Fed.Cir.), cert. denied, — U.S. -, 111 S.Ct. 537, 112 L.Ed.2d 547 (1990); Environmental Instruments, Inc. v. Sutron Corp., 877 F.2d 1561, 1566, 11 USPQ2d 1132, 1136 (Fed.Cir.1989); Sun-Tek Indus., Inc. v. Kennedy Sky Lites, Inc., 848 F.2d 179, 183, 6 *953USPQ2d 2017, 2020 (Fed.Cir.1988). This practice has been criticized as wasting public and private resources that have been expended in holding a patent invalid. See John Donofrio, The Disposition of Unre-viewable Judgments by the Federal Circuit, 73 JPTOS 462 (1991); Joseph R. Re & William C. Rooklidge, Vacating Patent Invalidity Judgments Upon an Appellate Determination of Noninfringement, 72 JPTOS 780 (1990).
When a patent has been finally adjudicated to be not infringed and further appellate review is not possible, there generally is no longer a case or controversy and the question of validity becomes moot. Altvater v. Freeman, 319 U.S. 359, 363, 63 S.Ct. 1115, 1117, 87 L.Ed. 1450, 57 USPQ 285, 288 (1943) (“To hold a patent valid that is not infringed is to decide a hypothetical case.”).1 Conversely, when a patent is similarly adjudicated as invalid, the infringement issue becomes moot. Sinclair & Carroll Co. v. Interchemical Corp., 325 U.S. 327, 330, 65 S.Ct. 1143, 1145, 89 L.Ed. 1644, 65 USPQ 297, 299 (1945). However, because this court is not a court of last resort, a holding of either invalidity or non-infringement by our court does not render the case moot because it is not over. Therefore, when both infringement and validity issues are presented on appeal, we can base our affirmance on both grounds, thereby leaving a complete judgment available for review by the Supreme Court.2 We are not compelled to address both or to address them in any order. The power to choose one or the other is not a matter of policy, but of discretion, considering the circumstances of the individual case. If we agree with the district court that no past, present, or future threat of infringement of a patent exists, there may be no need to address the issue of validity. Likewise, if we agree with the district court’s determination that a patent is invalid, there may be no need to address issues with respect to infringement.3 Our affirmance on either ground may render a decision as to the other unnecessary. Here, the circumstances illustrate that this court should answer the invalidity question, but need not deal with infringement.
The patents involved in this case have been through two full bench trials and are now before this court for the second time. As the Supreme Court noted in Blonder-Tongue Laboratories, Inc. v. University of Illinois Foundation, 402 U.S. 313, 328-29, 91 S.Ct. 1434, 1442-43, 28 L.Ed.2d 788, 169 USPQ 513, 519 (1971), there is “an arguable misallocation of resources” in permitting “a litigant more than one full and fair opportunity for judicial resolution of the same issue.”
If we vacate the invalidity holding here, as the panel has decided, this patentee will have a third opportunity to defend a patent that twice has been held invalid by a district court. This is not consistent with Blonder-Tongue and all parties lose. Morton, who has twice sued under its presumptively-valid patent and lost, still may feel that it can and must prosecute other suits. The presumption of validity has been shaken, but not destroyed. The public does not know whether it can practice the invention allegedly covered by a patent twice held invalid by a district court, but partially *954resurrected by this court. Even Cardinal, apparently a winner here because we have affirmed a finding of noninfringement, does not know whether this patent will obstruct future plans it may have in the field. Moreover, there is a public interest involved in the question of the validity of a patent. Sinclair, 325 U.S. at 330, 65 S.Ct. at 1145, 65 USPQ at 299 (“of the two questions [non-infringement and invalidity], validity has the greater public interest”).
In some cases, judicial economy may dictate that we affirm on noninfringement and vacate as to validity, but here, such action would add additional expense to the judicial costs, considering the multiple suits which Morton has brought. Bringing a patent action is an expensive and time-consuming endeavor, as is defending one.
All parties are entitled to a decision affirming or reversing the trial court’s holding of invalidity of these patents so that they can plan their future affairs accordingly. We can and should reach that issue.
35 U.S.C. § 112 requires that an invention be described “in such full, clear, concise, and exact terms as to enable any person skilled in the art ... to make and use the same.” At trial, Cardinal had the burden of proving lack of enablement of the '881 and ’845 patents by clear and convincing evidence. See 35 U.S.C. § 282. We review the court’s determination of lack of enablement as a question of law. Moleculon Research Corp. v. CBS, Inc., 793 F.2d 1261, 1268, 229 USPQ 805, 811 (Fed.Cir.1986), cert. denied, 479 U.S. 1030, 107 S.Ct. 875, 93 L.Ed.2d 829 (1987).
The specification purports to teach, with over fifty examples, the preparation of the claimed compounds with the required connectivity. However, on review of the record, there is considerable evidence showing that those skilled in the art could not make the claimed compounds using the procedures of the specification, and no evidence that such compounds even exist. The district court found that
[e]ven with the aid of sophisticated analytical instrumentation and the use of model systems which attempt to provide the compounds claimed in the '881 patent, however, there is no evidence that such compounds exist. The clear and convincing evidence has shown that the examples of the ’881 patent do not produce the postulated compounds. Rather, the examples and procedures produce a complex mixture of alkyltin mercaptides and alkyltin sulfides. The evidence established that a number of these are prior art compounds known to be useful as heat stabilizers.
The fifty-odd examples in the patent obviously teach something, but the evidence shows that they did not teach what was allegedly defined in the claims. Because Cardinal’s clear and convincing evidence was not rebutted by Morton, such as by showing that the examples do indeed produce the compounds containing the claimed connectivity, I see no error in the district court’s determination.
The statute also requires that the “specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.” 35 U.S.C. § 112. Since the claims at issue here are not sufficiently precise to permit a potential competitor to determine whether or not he is infringing, I would also agree with the district court’s determination that the claims are invalid for failure to satisfy the “definiteness” requirements of § 112, 2nd paragraph.
Given such a determination of invalidity, I would not address that part of the district court’s judgment regarding noninfringement.
. However, when a case arises consisting of a counterclaim for invalidity which is the subject of a cross-appeal or a separate appeal and the controversy between the parties extends beyond the litigated claims or the accused devices, the invalidity issue will not be moot. Altvater, 319 U.S. at 363-64, 63 S.Ct. at 1117-18, 57 USPQ at 288; Vieau, 823 F.2d at 1517-21, 3 USPQ2d at 1100-03 (Bennett, J., concurring).
. On a number of occasions, this court has reviewed, in precedential cases, both holdings. E.g., Mannesmantt Demag Corp. v. Engineered Metal Prods. Co., 793 F.2d 1279, 1280-81, 230 USPQ 45, 45 (Fed.Cir.1986); Shelcore, Inc. v. Durham Indus., 745 F.2d 621, 630, 223 USPQ 584, 591 (Fed.Cir.1984).
.Indeed, in a number of precedential cases, this court ruled on invalidity or unenforceability and either did not reach or vacated the non-infringement determination. E.g., Consolidated Aluminum Corp. v. Foseco Int'l Ltd., 910 F.2d 804, 808 n. 4, 15 USPQ2d 1481, 1483 n. 4 (Fed. Cir.1990); Dana Corp. v. IPC Ltd., 860 F.2d 415, 417, 8 USPQ2d 1692, 1694 (Fed.Cir.1988), cert. denied, 490 U.S. 1067, 109 S.Ct. 2068, 104 L.Ed.2d 633 (1989); A.B. Dick Co. v. Burroughs Corp., 798 F.2d 1392, 1393, 230 USPQ 849, 850 (Fed.Cir.1986).