In Simon v. Eastern Ky. Welfare Rights Organization, 426 U.S. 26 (1976), the respondents challenged an IRS Revenue Ruling that granted favorable tax treatment to nonprofit hospitals that offered only emergency-room services to the poor. The respondents argued that the Revenue Ruling "`encouraged' hospitals to deny services to indigents." 426 U.S., at 42. The Supreme Court held that the chain of causation was too attenuated: "It is purely speculative whether the denials of service . . . fairly can be traced to [the IRS's] `encouragement' or instead result from decisions made by the hospitals without regard to the tax implications. "It is equally speculative whether the desired exercise of the court's remedial powers in this suit would result in the availability to respondents of such services. So far as the complaint sheds light, it is just as plausible that the hospitals to which respondents may apply for service would elect to forgo favorable tax treatment to avoid the undetermined financial drain of an increase in the level of uncompensated services." 426 U.S., at 42-43.