Top court to rule on political spending limits

Next month, the Supreme Court will hear arguments over a case many are calling Citizens United 2.0.

Where Citizens United opened the door to unlimited spending by the so-called super political action committees (PACs), the new case—McCutcheon v. FEC—seeks to raise limits on political donations.

One analyst says the case—if ruled in the plaintiffs' favor—would only continue the massive influx of money into American politics by the few who can afford it.

"It reinforces a trend that's been happening for several years that was speeded up by Citizens United," said Bob Biersack, a senior fellow at the Center for Responsive Politics, a nonprofit research group that tracks the effect of money on politics.

"And that is a very small number of people become critical in campaigns because of their spending. In my opinion, if the Supreme Court allows this, any limits we would have on political spending would be less meaningful," he said.

(Read more: Market expects $15 billion Fed taper soon: CNBC survey)

The lawsuit revolves around a Republican donor and wealthy businessman from Alabama, Shaun McCutcheon, who wanted to give more money to candidates and political parties in 2012—be they state or national organizations—than is currently allowed by law. (McCutcheon is joined in the suit by the Republican National Committee.)

Arguments in the case are scheduled to begin on Oct. 8. The timing of a ruling is less certain, and could come as late as the summer of 2014.

Under the Citizens United 5-4 ruling from 2010, donors can give unlimited amounts of money to certain PACs—the so-called Super PACs. The Supreme Court held that the First Amendment prohibits the government from restricting politically independent expenditures by corporations, associations or labor unions.

But individual donors currently can give no more than $2,600 to any one federal candidate running for office and up to $48,600 spread among several candidates, every two-year election cycle.

And donors can give only up to $74,600 to a political party and traditional PACs for a total of $123,200, for the cycle.

(Read more: Summers withdrawal removes pressure to cut Republican deals)

In the suit, McCutcheon said he wanted to give a total of $75,000 to party committees and $54,400 to candidates in 2012—$6,200 more than the aggregate amount allowed by law. The RNC and McCutcheon claim the aggregate limits are "unsupported by any cognizable government interest ... at any level of review."

(McCutcheon is not challenging the individual limit, but the aggregate amount. The suit calls for no limits.)

The Supreme Court agreed earlier this year to hear the case after the U.S. Court of Appeals for the District of Columbia upheld the contribution limits already in place, by dismissing the lawsuit in September of 2012.

In its ruling, the lower court said that "the government may justify aggregate contribution limits as a means of preventing corruption or the appearance of corruption."

But one analyst said donor limits have their own limitations.

"It's worth noting that there is virtually no evidence that contribution limits per race have any effect on corruption or its appearance," said David Primo, a professor of political science at the University of Rochester who has researched the issue.

"I know people would disagree, but It's hard to imagine that limits on aggregate contributions would have any effect," he said.

Primo said that if the court rules in favor of the case, he doesn't see it as a watershed moment, any more than Citizens United.

"The fears over that (Citizens United) have not been realized, and I don't see this ruling changing much," Primo said.

"We're seeing more spending with every election, but I'm not sure this would increase what we've already seen," he said. "It just may make it easier to raise money. Candidates always find a way to raise money even with limits."

The total amount of money spent in the 2012 election—spent by candidates, political parties and outside groups like PACs—was an estimated $7 billion, the highest amount in American history, according to the Federal Election Commission.

Even with the Citizens United ruling, the majority of the cash came from small donors.

A report from liberal-leaning Demos and the U.S. Public Interest Research Group found that 40 percent of all contributions to U.S. Senate candidates and 32.5 percent to House candidates came from donors giving the maximum $2,500 contribution limit, but those donors amounted to just 0.02 percent of the American population.

If the Supreme Court rules in favor of McCutcheon, it would be the first time the high court has declared a direct contribution limit unconstitutional.

(Read more: Don't blame big banks for the crisis, say Dodd-Frank authors)

"It's not clear which way the court will go," said Biersack of the Center for Responsive Politics. "They have consistently made distinctions between spending money and giving money."

"Money doesn't guarantee success in politics, but if they eventually rule favorably in the case, I think it might shift the agenda in terms of policy choices politicians will make," Biersack contended.

"If someone gives a lot of money to a candidate," he said, "they expect something in return."

—By CNBC's Mark Koba. Follow him on Twitter @MarkKobaCNBC