Government watchdog groups that monitor corruption and the influence of special interests said the Supreme Court ruling opens the way for corporations and labor unions to exert even more influence on the elections process.

Bob Edgar is president of the monitoring group Common Cause:

"We need to recognize that money has influenced the debate here in Washington for too long," said Edgar. "All you have to do is look at the housing crisis, the investment crisis, the banking crisis. Even this health care debate was already tainted by how much money had flooded into the system. The elected officials in the House and Senate are going to end up serving special interests even more than they do today and not the public's interest."

The ruling will apply to this year's congressional midterm elections in November and could lead to a barrage of corporate and union sponsored television ads during the campaign that were previously restricted.

The case stemmed from a conservative group's challenge of campaign finance laws as part of an effort to promote a movie critical of then-presidential candidate Hillary Clinton in 2008.