Both parties have petitioned for a rehearing. Appellants seek a modification of that part of our opinion which directs a further hearing in the District Court. Appellees argue anew both questions decided against them.
An earnest desire to fairly meet counsel's argument, supplemented by an anxiety to avoid an erroneous conclusion, has caused us to again study the record, the opinion of the District Court, and the briefs of the opposing counsel. Appellees have favored us on this rehearing with two additional briefs, both longer than the original brief filed by them. They insist "that this court appears to stand alone in its refusal to follow the rule" supported by the unanimous decisions of the federal courts to the effect that a trial court's fact findings are unassailable where the evidence upon which they are based is conflicting.
If it be true, as asserted, that this court is out of harmony with all the other federal courts, we should readily correct our position. For it is not only our desire to follow the rule of the Supreme Court, but such a rule as appellees contend for, if it exists, will greatly lessen the work of this court, especially in patent litigation. The study of a record in a patent suit is a laborious task, and if the appellate court is bound by the District Court's finding on an issue of fact, be it on infringement, validity, the inventor's diligence, or the priority of the invention, a burdensome load will be lifted from our shoulders. We have assumed that not only this court, but all courts of appeal, have a duty to perform when an assignment of error raises the question of the sufficiency of the evidence to support the trial court's findings, which cannot be evaded or avoided by shielding ourselves behind the District Court's findings.
In considering such an assignment of error, we have assumed and uniformly held that the finding is presumably correct, but that it may be successfully assailed (a) if the physical facts demonstrate its unsoundness, (b) if the court clearly misapprehended the evidence or went against the clear weight of such evidence, (c) if the court applied an erroneous rule of law, which was necessary to the making of such finding, (d) if two fact-finding tribunals, on substantially the same evidence, reached different conclusions. In the latter case, this court will not give the same weight to the District Court's finding that it would give if such finding were not challenged by a contrary finding of another fact-finding tribunal.
In American Central Insurance Co. v. Harmon Knitting Mills, 39 F.2d 21, 24, we said: "True, this court must give and does readily give much weight to the District Court's finding upon this disputed issue. However we are not required to accept it in the same sense that we accept the verdict of a jury in an action of law respecting an issue over which there is a dispute."
There seems to be more reason for accepting without question the verdict of a jury in an action at law or in a criminal case than the finding of a court in an equity suit. Constitutional Amendment 7 provides "that no fact tried by a jury shall be otherwise reexamined, in any court of the United States, than according to the rules of the common law." No such constitutional or statutory pronouncement of the effect of a finding of a court in an equity suit exists.
Even in civil actions at law, however, the verdict of a jury is not conclusive, though there be some conflict in the evidence. In the recent case of Gunning v. Cooley, 281 U.S. 90, 50 S. Ct. 231, 233, 74 L. Ed. 720, the court had occasion to announce the rule in this language: "A mere scintilla of evidence is not enough to require the submission of an issue to the jury. the decisions establish a more reasonable rule 'that in every case, before the evidence is left to the jury, there is a preliminary question for the judge, not whether there is literally no evidence, but whether there is any upon which a jury can properly proceed to find a verdict for the party producing it, upon whom the onus of proof is imposed.'"
The rule governing the rejection of a finding of fact is not much different. It was stated in American Rotary Valve Co. v. Moorehead (C.C.A.) 226 F. 202, 203:
"There would be no occasion for a written opinion on denying a rehearing, except for the fact that counsel for appellant claim that we expressly or impliedly held, in so disposing of the case, 'that under the new equity rules the decision of the trial court upon a disputed question of fact is binding upon the review court.'
"We had no intention of being so understood. Under the new equity rules, as well as under the old ones, the reviewing court has the right, and owes to itself and to the parties the duty, of trying the questions of fact de novo. Under the old rules, the findings of the trial court were entitled to be treated as very persuasive, and such findings were not to be distutbed, unless it appeared quite clearly that the trial court had either misapprehended the evidence or had gone against the clear weight thereof. We conceive that the new rules have made no change in those respects."
Such differences of opinion as exist are usually traceable to the meaning of the language in (b), above, "if the court clearly misapprehended the evidence or went against the clear weight of such evidence." There might be differences of opinion as to when a finding is clearly contrary to the evidence, but there should be no difference as to the rule itself.
The case of Corona Cord Tire Co. v. Dovan Corp., 276 U.S. 358, 48 S. Ct. 380, 72 L. Ed. 610, is worthy of special attention. There the court said, page 375 of 276 U.S., 48 S. Ct. 380, 385: "It is also claimed that because the trial court in this cause found, after hearing the witnesses, the weight to be with the petitioner and against Weiss, assignor of respondent, its conclusions of fact, except for manifest error, are to be treated as unassailable. Adamson v. Gilliland, 242 U.S. 350, 353, 37 S. Ct. 169, 61 L. Ed. 356; Davis v. Schwartz, 155 U.S. 631, 15 S. Ct. 237, 39 L. Ed. 289; Kimberly v. Arms, 129 U.S. 512, 9 S. Ct. 355, 32 L. Ed. 764; Tilghman v. Proctor, 125 U.S. 136, 149, 8 S. Ct. 894, 31 L.eD. 664; and Mason v. United States, 260 U.S. 545, 556, 43 S. Ct. 200, 67 L. Ed. 396. We do not think that this rule applies in the case before us, at least to its full extent, first, for the reason that the Circuit Court of Appeals, having considered all the evidence upon which the trial judge reached his conclusion, declined to approve of his findings, and, second, because in the National Aniline & Chemical Co. Case [(C.C.A.) 262 F. 555]), which is in conflict with the case here, the trial judge reached a different conclusion on the same issue and the same evidence which we have here."
The Ninth Circuit Court of Appeals has had occasion to discuss this question in Carson Inv. Co. v. Anaconda Copper Mining Co., 26 F.2d 651, 661. The court said: "We are mindful that the evidence as to prior use is conflicting, and that there is testimony that there was a practice of sidecharging in the smelters at Dollar Bay. But in patent litigation the mere fact that there is a serious conflict in the evidence as to prior public use, and that the District Court has made its findings in favor of defendants in ...