This is a suit against the Roto Company and Philip J. Darlington, its president, for infringement of United States letters patent No. 983,032, for turbines, and No. 1,045,134, for rotary motor, duly assigned to the complainant.
The sole question to be determined is whether the defendants are bound by a decree in favor of the complainant in a prior suit instituted by it on the same patents in the District Court of the United States for the Western District of Pennsylvania against one Robertson, a seller of the same motor manufactured by the defendant, the
[1-3] The defendant objects that its defense of the prior suit was not open and avowed, and that, because it did not know that the complainant was aware it was defending the case, there can be no estoppel for want of mutuality. In other words, it says that a decree in favor of the defendant in that case would not have been res adjudicata in a subsequent suit by the complainant against it. It is quite true that an estoppel, to be effective, must be mutual. The principle has been expressed in various cases by saying that a defense conducted by a third party “must be open and avowed,” or “must be known to the opposite party.” Either category in our opinion is sufficient. Cramer v. Singer Co., 93 Fed. 636, 35 C. C. A. 508; Hanks v. Dental Association, 122 Fed. 74, 58 C. C. A. 180; Penfield v. Potts, 126 Fed. 475, 61 C. C. A. 371; Jefferson Co. v. Westinghouse Co., 139 Fed. 385, 71 C. C. A. 481.
When the defense is not open or avowed, the estoppel becomes matter of proof. If the plaintiff relies upon it, he must show that the defendant actually did conduct the defense in the prior suit. If the defendant relies on it, he must show not only that he did conduct the defense, but that the plaintiff knew he did. In the present case the Roto Company did not directly avow that it was defending the suit against Robertson, nor authorize him to inform the Elliott Company of that fact. Its intention was to conceal what it was doing. All the same, it was defending the suit. Robertson did inform the Elliott Company of the fact, and the defendant Darlington, president of the Roto Company, did openly participate to some extent. We do not think it was necessary that the defendant should have known that the claimant was aware that it was defending the suit against Robertson to make the estoppel effective. If the decree had been in favor of Robertson, and the Roto Company could have proved that the complainant knew that it had defended that suit, which we have little doubt it could have done, then the decree would have been res adjudicata against the complainant in a subsequent suit.
Decree affirmed.