A case headed to the Supreme Court could upend longstanding rules limiting federal political contributions. The Republican National Committee and an individual plaintiff filed an appeal yesterday after a three-judge panel of the U.S. District Court for the District of Columbia rejected their challenge to limits on the total amount an individual may contribute over a two-year period in connection with federal elections.

The Supreme Court is required to hear the case under a provision in the Bipartisan Campaign Reform Act (McCain-Feingold) authorizing direct appeals to the Court. A ruling striking down the federal limits could raise questions about a host of similar state laws, such as a Maryland law limiting aggregate contributions to $10,000 over a four-year election cycle and a New York law imposing an annual $150,000 limit on an individual’s total contributions to state political committees.

This is how the federal aggregate limits work. Between January 1, 2011, and December 31, 2012, an individual may contribute no more than $117,000 to federal political committees. Of that amount, no more than $46,200 may be contributed to federal candidates. Another $70,800 may be contributed to federal PACs and political parties, of which only $46,200 may be given to a combination of federal PACs and the federal accounts of state and local party committees. A new two-year cycle, with adjusted limits, will begin on January 1 of next year.

Do aggregate limits prevent corruption, which the Supreme Court has recognized as the only governmental interest that can justify restricting free speech rights?

As the three-judge panel noted, the Supreme Court has rejected the notion that merely spending a lot of money to support candidates is inherently corrupting. And since each individual contribution is subject to a $2,500 per election limit, it is difficult to see how any one contribution could corrupt a recipient candidate. That leaves only the argument that contributions to Candidates A, B, and C somehow threaten to corrupt Candidate D whom the contributor did not support. Surely, though, if independent expenditures by outside groups do not buy influence with candidates (which the Supreme Court held in Citizens United), then this attenuated corruption theory stands no chance of prevailing.

The district court panel suggested that the aggregate limits may help prevent circumvention of the $2500 per election limit on contributions to a particular candidate. A half million dollar contribution allocated among party committees could be transferred to a single party committee (there are no limits on transfers between committees of the same party), which could then coordinate its spending with a candidate. However, if a contributor earmarked a contribution in this manner it would be treated as an excessive (and therefore illegal) contribution to the candidate. And if the contributor had no knowledge of the transfer scheme, then his contribution could not plausibly be viewed as an effort to buy influence with the candidate.

Noting that it was constrained by prior Supreme Court precedent, the three-judge panel warned that the case “raise[s] the troubling possibility that Citizens United undermined the entire contribution limits scheme.”

Indeed it does. Yet another bedrock principle of campaign finance law may be in for a jolt.