Republican activist Shaun McCutcheon of Hoover, Ala., the national Republican Party and Senate GOP leader Mitch McConnell of Kentucky want the court to overturn the overall limits — $123,200, including a separate $48,600 cap on contributions to candidates, for 2013 and 2014. McCutcheon and McConnell attended Tuesday's argument.
The limit on individual contributions to any candidate for Congress in any given election, currently $2,600, is not at issue in this case.
Solicitor General Donald Verrilli, the Obama administration's top Supreme Court lawyer, struggled to persuade conservative justices who are skeptical of campaign finance laws that the overall limits serve as a check on corruption. Without them, Verrilli said, donors could write checks of more than $3.5 million and noted that non-presidential election cycles cost a political party and its candidates roughly $1.5 billion.
Absent limits, "less than 500 people can fund the whole shootin' match," Verrilli said.
But Justice Antonin Scalia said that in an era of unlimited independent spending, "I don't think $3.5 million is a heck of a lot of money." The other members of the Citizens United majority, Justices Samuel Alito and Anthony Kennedy also questioned Verrilli's argument and Justice Clarence Thomas, who asked no questions as is his custom, has long opposed campaign limits.
The court's four liberal justices appeared inclined to uphold the limits at issue.
McCutcheon, owner of the Coalmont Electrical Development Corp. in McCalla, Ala., said he will spend a few hundred thousand dollars in the current election cycle, including large donations to so-called super PACs that are not affiliated with candidates.
In 2011 and 2012, McCutcheon gave the symbolically significant $1,776 to 15 candidates for Congress and wanted to give the same amount to 12 others. But doing so would have put him in violation of the cap.
The Republican challengers are asking the court to take an even more aggressive approach than merely overturning these particular limits. McConnell is leading the charge to urge the justices to ditch their practice over nearly 40 years of evaluating limits on contributions less skeptically than restrictions on spending.
The differing levels of scrutiny have allowed the court to uphold most contribution limits, because of the potential for corruption in large direct donations to candidates. At the same time, the court has found that independent spending does not pose the same risk of corruption and has applied a higher level of scrutiny to laws that seek to limit spending.
If the court were to drop the distinction between contributions and expenditures, even the per-election contribution limit of $2,600 to any candidate for Congress would be threatened, said Fred Wertheimer, a longtime supporter of stringent campaign finance laws.
"This is not about some abstract concept of aggregate limits. It's about re-establishing a system where huge contributions can be given directly to benefit candidates and parties, and it will create opportunities for the corruption of governmental decisions," said Wertheimer, president of the nonpartisan Democracy 21 group.
In recent years, opponents of campaign finance laws have won a string of victories at the Supreme Court, typically by a 5-to-4 vote with the court's conservative justices in the majority. Their winning streak dates to the replacement of Justice Sandra Day O'Connor, who often voted to uphold campaign limits, by Justice Samuel Alito, who is far more skeptical of the restrictions.
The sweep of the decision could come down to the willingness of Alito and Roberts to join their three conservative colleagues, Kennedy, Scalia and Thomas, in pushing for a tougher review of laws that limit contributions. Those three justices already have said they would consider doing away with the distinction between campaign giving and spending.