Appellants, plaintiffs below, appeal from an order of the District Court granting appellee's motion to dismiss under Rule 12(b)(6), Fed.R.Civ.P., for failure to state a claim upon which relief can be granted.

Appellants brought suit against the McDonnell Aircraft Corporation (McDonnell) under 35 U.S.C. 271 for infringement of patent No. 2,378,328 during the period November 23, 1960 to June 12, 1962. Appellants' patent involves the use of certain radioactive isotopes to identify and distinguish certain products from similar products of other manufacturers. The insertion of radioactive materials into these products imparts a harmless amount of radioactivity to them which is easily detectable by means of a Geiger counter.

The complaint alleged that McDonnell infringed this patent by manufacturing and using, without license, various types of apparatus employing the principle of appellants' patent.1

McDonnell responded to the complaint by filing a motion to dismiss, accompanied by supporting affidavits, under Rule 12(b)(6) for failure to state a claim for relief. The affidavits, filed by McDonnell's officers and engineers, stated in substance:

(1) That all aircraft manufactured during the relevant period were noncommercial aircraft manufactured exclusively for the United States Government;

(2) That McDonnell utilized 'bucking bars' containing radioactive materials solely in aircraft manufactured for the United States Government;

(3) That all contracts under which McDonnell manufactured aircraft for the United States contain 'authorization and consent' clauses.2

Appellants opposed McDonnell's motion to dismiss by way of a counter affidavit of their attorney, Robert H. Rines. Attached to this affidavit as exhibits were copies of pages from McDonnell's annual reports for the years 1959, 1960 and 1962, respectively, which indicated that defendant had manufactured a prototype civilian airplane, designated as Model '220.'

McDonnell then filed supplemental affidavits indicating that the only use of radioactive materials between November 23, 1960 and June 12, 1962 was in bucking bars, and that a single model 220 civilian aircraft was manufactured and completed prior to the relevant damage period.

Despite its consideration of the accompanying affidavits, the District Court nonetheless proceeded to decide the case on written briefs as if it were a motion to dismiss the complaint under Rule 12(b)(6). The Court, in granting the motion to dismiss, concluded that if McDonnell's use of radioactive materials in bucking bars infringed appellants' patent, the latters' sole and exclusive remedy was a suit against the United States in the Court of Claims under 28 U.S.C. 1498, and therefore the Court was without jurisdiction to hear appellants' complaint. Evans v. McDonnell Aircraft Corporation, 270 F. Supp. 778, 780-781 (E.D.Mo.1967).

In dismissing the complaint the District Court purported to act on the basis of a Rule 12(b)(6) motion to dismiss. That Rule explicitly provides, however, that if the Court in ruling on the motion takes into consideration matters outside the pleadings, it must treat the motion as one for summary judgment under Rule 56.3

Since both parties filed affidavits and exhibits in support of their respective positions, which were not excluded by the District Court, the motion to dismiss should properly have been treated as one for summary judgment. Costen v. Pauline's Sportswear, Inc., 391 F.2d 81, 85 (9th Cir. 1968); Central Contracting Co. v. Maryland Casualty Co., 367 F.2d 341, 343 (3rd Cir. 1966); Smith v. United States, 362 F.2d 366, 367-368 (9th Cir. 1966).

Considering the motion therefore as one for summary judgment the crucial question is whether this case presents a genuine issue as to some material fact. Unless the pleadings and supporting documents disclose beyond any doubt the absence of a genuine issue of fact, summary judgment should not be entered. Poller v. Columbia Broadcasting System, Inc., 368 U.S. 464, 467, 82 S. Ct. 486, 7 L. Ed. 2d 458 (1962); Vineberg v. Brunswick Corporation,391 F.2d 184, 187 (5th Cir. 1968); Williams v. Chick, 373 F.2d 330, 331-332 (8th Cir. 1967); Kennedy v. Bennett, 261 F.2d 20, 22 (8th Cir. 1958); Booth v. Barber Transportation Co., 256 F.2d 927, 928 (8th Cir. 1958).

From our examination the record reveals a material issue of fact as to whether McDonnell's manufacturing operations were exclusively oriented to the United States Government. Appellants, by way of counter affidavit and accompanying exhibits, directly controverted McDonnell's assertion that only non-commercial Government aircraft were manufactured during the period of alleged infringement. We have consistently held that genuine issues of material fact cannot be determined on the basis of affidavits. Booth v. Barber Transportation Co., supra; Ford v. Luria Steel & Trading Corp., 192 F.2d 880, 882 (8th Cir. 1951).

We are mindful of McDonnell's contention that during the period in issue its production of aircraft was solely for the United States Government under contracts containing 'authorization and consent' clauses, which have the effect of relegating appellants to an action against the United States in the Court of Claims. As noted, appellants' documentary evidence refutes the assertion that aircraft were manufactured 'solely' for the Government. Additionally, they submit that the complete Government contracts were not before the District Court; that the documents filed were only fragmentary portions of certain contracts and consequently the District Court could not advisedly determine whether specific authorization and consent for the use of appellants' patent was given or intended in the contracts. Upon remand this and other facets of the case can be fully developed by appropriate proceedings.

The judgment of dismissal is vacated and the case is remanded for further proceedings.