In the case of Vendo Co. v. Lektro-Vend Corp., et al., 1977, the U.S Supreme Court was asked to consider whether a federal court could enjoin state court proceedings under certain circumstances in an antitrust lawsuit. The Vendo Company had filed a patent infringement suit against Lektro-Vend Corporation and others in Illinois state court while simultaneously facing an antitrust action from Lektro-Vend in federal district court for alleged monopolistic practices related to vending machine patents. When Vendo sought to have its patent claim heard first, it requested that the federal judge issue an injunction halting proceedings at the state level until after resolution of their own case. The Supreme Court held that despite exceptions outlined by Congress allowing for such actions when necessary "to protect or effectuate its judgments," this did not apply here as there were no exceptional circumstances warranting interference with ongoing parallel litigation at both levels of jurisdiction concurrently. Therefore, they ruled that it was inappropriate for a federal judge to halt proceedings within another judicial system without explicit statutory authority permitting them to do so.

In the dissenting opinion for Vendo Co. v. Lektro-Vend Corp., Justice Brennan, joined by Justices White and Marshall, argued that federal courts should not be barred from hearing antitrust cases simply because a state court is simultaneously hearing a similar case involving the same parties. They believed this would undermine the role of federal courts in enforcing national antitrust policy. The dissenters also disagreed with the majority's interpretation of an earlier Supreme Court decision (Princess Lida v Weis), arguing it did not establish such broad restrictions on concurrent jurisdiction between state and federal courts as suggested by the majority ruling in this case.