In the 1990 case of Robert L. McCormick v. United States, the Supreme Court ruled on whether campaign contributions could be considered bribes under federal law. The defendant, a West Virginia state legislator named Robert McCormick, had accepted money from a lobbyist and then pushed for legislation favorable to that lobbyist's interests. He was convicted under the Hobbs Act for extortion but appealed his conviction arguing that he received these funds as legitimate campaign contributions rather than bribes. The Supreme Court overturned McCormick's conviction in a 5-4 decision stating that evidence of an explicit quid pro quo agreement is necessary to convict public officials for receiving unlawful payments under the Hobbs Act when they are accepting campaign donations. In other words, it must be clearly demonstrated that there was an agreed upon exchange - payment in return for specific official action - not just coincidental timing between contribution receipt and legislative activity favoring donor’s interest.

In the dissenting opinion for McCormick v. United States, Justice Scalia argued that the majority misinterpreted the Hobbs Act by applying it to a situation where there was no clear evidence of quid pro quo corruption. He contended that campaign contributions should not be considered as bribes unless there is explicit proof of an agreement between the donor and recipient in which official actions are exchanged for donations. In this case, he believed such evidence was lacking and thus disagreed with convicting McCormick under the Hobbs Act based on his acceptance of campaign funds from lobbyists seeking legislative favors. Furthermore, he criticized how broadly federal prosecutors could interpret "extortion" under this ruling, potentially criminalizing common political practices and infringing upon states' rights to regulate their own electoral processes.