Justice Samuel Alito, who joined the court in 2006, sided with a five-member majority in last week's opinion. His predecessor, Justice Sandra Day O'Connor, sided with four other justices in 2003 to uphold the central provisions of a sweeping campaign-finance law Congress approved in 2002.
"The climate on the Supreme Court is different, and people like James Bopp see the opportunity to recast campaign-finance legislation," Roberts said. "The big question is how far the court is willing to go."
Fred Wertheimer of the watchdog group Democracy 21 said advocates of campaign-finance limits intend to fight back in the courts and on Capitol Hill, where they are pushing legislation for taxpayer funding of congressional elections. Other bills under consideration include a measure requiring corporate executives to appear in any ads they fund.
"This a political battle that is ongoing," Wertheimer said, "and the fact that the court made a disastrous and irresponsible decision is not going to stop us from being aggressive in pursuing our goals."
Recent court rulings have eroded federal campaign-finance limits:
2007 | Wisconsin Right to Life v. Federal Election Commission (FEC) | Supreme Court allows labor, business and other groups to run issue ads that mention candidates by name in the final days before an election, a practice that had been outlawed under a 2002 campaign-finance law.
2008 | Davis v. FEC | Supreme Court strikes down the so-called millionaire's amendment, which allowed federal candidates to raise three times the legal limit if they were competing against wealthy candidates bankrolling their own campaigns.
2009 | EMILY's List v. FEC | A three-judge panel of a federal appeals court rules to allow non-profits to raise unlimited amounts of money to independently support or oppose federal candidates. That strikes down a Federal Election Commission rule that imposed a $5,000 cap on what individuals could give to politically oriented non-profits, such as EMILY's List, which supports female candidates who favor abortion rights. A full appellate court will take up a similar case this week.
2010 | Citizens United v. FEC | Supreme Court allows corporations and unions to tap their treasuries to spend unlimited amounts on campaign ads that call for the election or defeat of federal candidates.