''The virtues of a bright-line rule surely cannot alone justify regulating constitutional speech."

The Federal Election Commission loses in its effort to enforce the McCain-Feingold law against issue ads that mention the name of a candidate.

Wisconsin Right to Life, an anti-abortion group, has been fighting the law since 2004, when it sought to run an advertisement urging voters to contact Wisconsin Sens. Russ Feingold and Herb Kohl, both Democrats, and ask them not to hold up President Bush's judicial nominees.

Because Feingold was running for re-election in 2004, the ad was prohibited. Wisconsin Right to Life argued that it wasn't trying to influence an election and said the law restricted its constitutional right to petition the government.