The Supreme Court on Monday seriously weakened a key feature of the McCain-Feingold campaign finance law, possibly ushering in a new era of high court disapproval of measures aimed at reining in campaign excesses.

“Enough is enough,” Chief Justice John Roberts Jr. wrote, referring to the expansion of government restriction on campaign speech that should be protected by the First Amendment. “Where the First Amendment is implicated, the tie goes to the speaker, not the censor.”