concurring.
While I agree with the majority that the issue was not properly raised in this case (ante at 1353 n. 2), I wish to add a word of caution concerning the determination of issues of alleged prior inventor credibility on summary judgment. It is one thing to find, after trial, that the alleged prior inventor’s testimony is sufficiently corroborated to support a verdict of invalidity. See, e.g., Mahurkar v. C.R. Bard, Inc., 79 F.3d 1572, 1578-79, 38 USPQ2d 1288, 1292 (Fed.Cir.1996) (district court proceeding with testimony of witnesses). It is quite another to hold that no trial is required in the first place. Even where our corroboration requirement is satisfied, in many cases summary judgment cannot be granted unless the prior inventor’s testimony is considered to be credible. Even where there are no affidavits from the party opposing judgment (the patent holder), it will often be appropriate to deny summary judgment because the prior inventor’s testimony raises issues of credibility that require a trial.
The Advisory Committee Note for Rule 56 of the Federal Rules of Civil Procedure explicitly recognizes that summary judgment is inappropriate in circumstances where credibility is an issue, stating: “Where an issue as to a material fact cannot be resolved without observation of the demeanor of witnesses in order to evaluate their credibility, summary judgment is not appropriate.” Advisory Committee Note to the 1963 Amendment, Fed. R.Civ.P. 56. This principle has been applied in cases such as Cross v. United States, 336 F.2d 431 (2d Cir.1964), holding that where issues of credibility exist, a reversal of a grant of summary judgment is required so that the non-moving party may test a witness’s credibility on cross-examination. Id. at 433. In Cross, an assistant professor of romance languages sought a tax refund for expenses incurred in connection with his summer travel to various parts of Europe and the Mediterranean. Id. at 432. The professor contended that the purpose of the trip was to improve his language skills and extend his contacts with foreign cultures. Id. He supported his motion for summary judgment with a discovery deposition of himself (i.e., without cross-examination) and affidavits of several other professors. Id. at 431-32. The government filed no evidence in response, only claiming a right to cross-examine Cross and the affiant professors. Id. at 432. The district court granted summary judgment for Cross. On appeal, the Second Circuit held that while “ordinarily the bare allegations of the pleadings, unsupported by specific evidentiary data, will not alone defeat a motion for summary judgment, this principle does not justify summary relief where, as here, the disputed questions of fact turn exclusively on the credibility of movants’ witnesses.” Id. at 433 (internal citations omitted). The • court therefore reversed the summary judgment grant and remanded for a trial. Id. at 434.
It is particularly questionable whether summary judgment should be granted in prior inventorship cases based on the affidavit of the alleged earlier inventor. As *1358we have repeatedly recognized, the affidavit of an alleged infringer seeking to establish prior inventorship is inherently suspect. See Woodland Trust, 148 F.3d at 1371, 47 USPQ2d at 1366 (“Throughout the history of the determination of patent rights, oral testimony by an alleged inventor asserting priority over a patentee’s rights is regarded with skepticism (quoting Price v. Symsek, 988 F.2d 1187, 1194, 26 USPQ2d 1031, 1036 (Fed.Cir.1993)); see also Singh v. Brake, 222 F.3d 1362, 1367, 55 USPQ2d 1673, 1676 (Fed.Cir.2000) (“[The corroboration] rule addresses the concern that a party claiming inventorship might be tempted to describe his actions in an unjustifiably self-serving manner in order to obtain a patent or to maintain an existing patent.”); Mahurkar, 79 F.3d at 1577, 38 USPQ2d at 1291 (stating that the corroboration requirement “arose out of a concern that inventors testifying in patent infringement cases would be tempted to remember facts favorable to their case by the lure of protecting their patent or defeating another’s patent”).
However, I agree with the majority that these credibility issues, as opposed to the corroboration issues, have not been properly raised in this ease.