Some political experts say a ruling in favor of increased, or even unlimited, aggregate individual donor contributions could put party committees and political action committees on a greater competitive track with the "super PACs."
All PACs are organizations that campaign either for or against candidates, legislation, or ballot measures. The difference is in how they are organized for regulatory and tax purposes, and by the amounts of money they are allowed to spend.
Regular PACs may also give limited donations to federal candidates and political parties, while super PACs cannot.
Legal, political fallout
If they win at the high court, wealthy donors like McCutcheon -- whether Democrat, Republican, or Independent -- could in theory contribute a maximum $3.6 million to the national and state parties, and the 450 or so Senate and House candidates expected to run in 2014.
Key for the conservative majority court is whether the current law has a permissible goal of preventing political corruption or the appearance of it. And both sides of the legal fight have entrenched views on that.
"Limitations on a citizen's First Amendment rights cannot be drawn to target the most outlandish hypotheticals that interest groups can conceive," said the National Republican Senatorial Committee and National Republican Congressional Committee in a legal brief. "Especially where those interest groups have an interest in manufacturing the 'appearance' of corruption that this court has held can justify campaign finance regulation."
But those who want current controls to remain in place say if aggregate contribution limits to candidates or parties disappear, it would make it easier for the money to get routed by party leaders into other close races nationwide.
"If the court continues in the direction of Citizens United," said Sen. Elizabeth Warren (D-Massachusetts) in a recent speech sponsored by the progressive Constitutional Accountability Center, "we may move another step closer to neutering Congress' ability to limit the influence of money in politics and another step closer to unlimited corporate contributions given directly to candidates and political committees."
What is the impact?
Another point of contention is whether the aggregate spending limits are really having a pervasive effect, or only involve a relative few well-heeled givers.
Figures from the Center for Responsive Politics for the 2012 race showed about 600 donors leveraged their money to each give the maximum of about $48,000 total -- benefitting no more than 17 presidential or congressional candidates. Almost 1700 contributors forked over the maximum limit to party committees, which added up to more than $100 million. Loosening those limits, say opponents of the law, would benefit wealthy liberals and conservatives equally.
But the Supreme Court has never in its history overturned a federal contribution limit.
"Now imagine that overall contribution limits are struck down. Presidential candidates in 2016 could solicit and each of these donors could contribute as much as $1.2 million to their joint fundraising committees" said Fred Wertheimer, founder and president of Democracy 21, a longtime activist on campaign spending reform. "It may well open the door to striking down all of the remaining contribution limits, taking us back to the robber-baron era."
The presidential campaigns of Obama and his Republican opponent Mitt Romney were able to create joint fundraising committees and, working with their respective parties, pool fundraising resources. That meant those campaigns were able to solicit contributions to the maximum $70,800 per donor.
Wertheimer says an end to contribution limits would be an "unmitigated disaster."
But McCutcheon argues that characterizing the legal fight as between "good" and "bad" simply blurs the truth.
"Getting rid of the aggregate limits is not about corrupting democracy-- it is about practicing democracy," he said. "This case is about freedom-- your freedom and my freedom-- to express ourselves openly and fully within our political system. And if there is one thing that we Americans believe with all our hearts, it is that freedom never corrupts."
The case is McCutcheon v. Federal Election Commission (12-536).