P brought a class action on behalf of herself and all persons in the United States who purchased hearing aids manufactured by Sonotone (Ds). P alleges that Ds violated §§ 1 and 2 of the Sherman Act and 2, and § 3 of the Clayton Act. P claims Ds restricted the territories, customers, and brands of hearing aids offered by their retail dealers, used the customer lists of their retail dealers for their own purposes, prohibited unauthorized retailers from dealing in or repairing their hearing aids, and conspired among themselves and with their retail dealers to fix the retail prices of the hearing aids. Ds moved for dismissal of the complaint in that Ps lacked standing to sue for treble damages under § 4 of the Clayton Act because she had not been injured in her 'business or property' within the meaning of the Act. The District Court held that under § 4 a retail purchaser is injured in 'property' if the purchaser can show that antitrust violations caused an increase in the price paid for the article purchased. It then certified the question for interlocutory review under 28 U. S. C. § 1292 (b). The Court of Appeals reversed, holding that retail purchasers of consumer goods and services who allege no injury of a commercial or business nature are not injured in their 'business or property' within the meaning of § 4. The phrase 'business or property' was intended to limit standing to those engaged in commercial ventures. Differing views on this issue have been expressed by various courts. The Supreme Court granted certiorari.