Moreover, the Supreme Court has reaffirmed the conclusion in "Standard Oil" that analysis under the rule of reason should focus on the economic but not the social consequences of a restraint ("National Society of Professional Engineers v. United States", 435 U.S. 679 (1978)). Further, the Court retained the "per se" rule against tying contracts but raised the threshold showing of market power that plaintiffs must make to satisfy the rule's requirement of "economic power" (see "Jefferson Parish Hospital District No. 2 v. Hyde", 466 U.S. 2 (1985).