McCutcheon, who has the backing of Senator Mitch McConnell, (R-Ky.), is fighting the federal overall cap on money a person can give to candidates or political parties during a two-year election cycle.
Federal
McCutcheon is just challenging the aggregate $123,000 cap. If the Supreme Court does away with the two-year cap, however, the wealthy could provide millions of dollars to a political party through various candidates or a single "joint fundraising committee," the advocacy group Demoracy 21 says.
Without the cap, the group says, "we would be back to the same kind of huge contributions that constituted legalized corruption and resulted in the Watergate scandals in the 1970s."
The Supreme Court's conservative majority is already not a huge fan of
McCutcheon's crusade against individual spending limits is just "another Citizens United - but worse," as the legal analyst Jeffrey Toobin wrote in The New Yorker. Despite what some people think, Citizens United didn't let corporations give as much money as they wanted to political candidates. Citizens just lets Corporate America spend freely on groups that endorse campaigns (otherwise known as Political Action Committees, or PACs.)
McCutcheon's case could give rich people more influence by letting them spend wildly on a single political party by giving to various candidates who belong to that party.
The wealthy could even have a lot of influence over single candidates through so-called joint fundraising committees, according to Democracy 21. Candidates work together to raise money through those committees, which are currently subject to the overall cap McCutcheon is fighting. Without that cap, donors could contribute much more money to joint-fundraising campaigns - potentially millions depending on how many state parties and party committees are participating.
Congress enacted campaign finance limits to stop this kind of spending back in the 70s after Watergate. The notorious hotel break-in eventually exposed the Nixon campaign's efforts to bully companies into giving political contributions, according to a good overview of the scandal on CNN.com. Those companies wanted favors in return.
"There was a widespread public perception that the political process had been thoroughly corrupted," Cornell Law Professor Robert Hockett told CNN. "Public policy seemed to be up for sale to the highest bidder."
The Supreme Court has gradually picked away at Congress' post-Watergate attempts to improve the public's perceptions of the nation's lawmakers. Not long after the reforms were passed, in 1976, the court did away with limits on the amount of money candidates could spend on campaigns.
The McCutcheon decision this fall will likely be the court's next move to let money flow a little more freely into lawmakers' pockets given the current composition of the Supreme Court. The court's four liberal justices will probably vote to keep caps on individual spending, and the four conservative justices will opt to kill them.
Swing voter Anthony Kennedy, who will probably cast the deciding vote, has already shown his hostility for campaign finance limits. He wrote the majority opinion in Citizens United, which found corporations had a First Amendment right to "political speech."
"Citizens United was not an aberration for this Court," Jeffrey Toobin wrote for The New Yorker. The justices in the majority, he added, are "engaging in a long-term project to deregulate campaigns."