[4] Morton sued Suppiger and the district court dismissed the complaint on summary judgment because of "plaintiff's use of its patent to develop a monopoly of an unpatented article, to-wit, salt tablets.

"However, unlawfulness is made to depend upon a provision which is here important, where the effect of such lease or such condition may be substantially to lessen competition or tend to create a monopoly in any line of commerce."

Chief Justice Harlan Stone delivered the opinion of the Court, unanimously reversing the judgment of the Seventh Circuit.

It is well recognized that "courts of equity may appropriately withhold their aid where the plaintiff is using the right asserted contrary to the public interest.

"[9] The proper rule in such cases, the Court said, is: Where the patent is used as a means of restraining competition with the patentee's sale of an unpatented product, the successful prosecution of an infringement suit, even against one who is not a competitor in such sale, is a powerful aid to the maintenance of the attempted monopoly of the unpatented article, and is thus a contributing factor in thwarting the public policy underlying the grant of the patent.

Maintenance and enlargement of the attempted monopoly of the unpatented article are dependent to some extent upon persuading the public of the validity of the patent, which the infringement suit is intended to establish.

[12] These considerations made it unnecessary, the Court added, to decide whether Suppiger had committed an antitrust violation "for we conclude that, in any event, the maintenance of the present suit to restrain petitioner's manufacture or sale of the alleged infringing machines is contrary to public policy, and that the district court rightly dismissed the complaint for want of equity."

The Seventh Circuit, in Panther Pumps & Equipment Co. v. Hydrocraft, Inc.,[15] effectively limited Suppiger by holding that violations of the rule in Lear, Inc. v. Adkins,[16] against agreements not to challenge patent validity should not lead to the harsh result of making the patent unenforceable against infringement, because such an agreement was "not the kind of misuse which forecloses recovery of damages" from an infringer.