How have courts treated declaratory judgments relating to patents?

Since the enactment of the Declaratory Judgments Act (28 U.S.C.A. 400), courts have entertained declaratory judgments relating to patents where the plaintiff sought declaration of validity or invalidity of a patent, and whether there had been an infringement or not. A review of these cases may be found in the writer's opinion in Hann v. Venetian Blind Corporation (D. C.) 15 F.Supp. 372, 30 U.S.P.Q. 112. So if the plaintiff alleged that he is infringing the defendant's patent, and sought either relief or declaration against the actual or threatened acts of the defendants, his amended and supplemental complaint would have to be sustained. But he does not allege that he is guilty of infringement or contributory infringement. He avoids a direct allegation of either. Nor does he allege that the defendant claims that he is infringing or has threatened any suit against him, or that he is under legal liability to the defendant, or that any of his acts are or have been an infringement of patent No. 1,965,876. In other words, no legal relationship, cognizable under the patent laws, appears from the amended complaint. It is true that, parenthetically, here and there, the plaintiff, in his bill, speaks of acts upon his part which, if alleged directly, might constitute infringement or contributory infringement. But these allegations fall short of the directness necessary to treat them as statements of fact.