So Citizens United appears to be a goner at the first opportunity. But how much difference will that make? Much less than people think.

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First, the vast majority of political money in the United States still comes from individuals. Corporate and union spending remains below 10 percent of total political spending in the United States.

Second, overruling Citizens United will not automatically eliminate super PACs. Constitutional protection for super PACs hinges not on Citizens United but on SpeechNow.org v. Federal Election Commission, a unanimous decision by the U.S. Court of Appeals for the D.C. Circuit (which included Garland). Though the opinion in Speechnow.org cited Citizens United, the plaintiffs actually based their case—briefed before Citizens United was decided—on older Supreme Court cases, including Buckley. So Speechnow.org could survive even if Citizens United were overturned.

And even if Speechnow.org itself were reversed along with Citizens United, corporations (and unions) would remain free to spend on ads intended to sway the public on issues. And pursuant to Buckley, more than 60 days before the general election or 30 days before a primary, such ads can discuss candidates as well as issues, so long as they refrain from “expressly advocating” that voters support or defeat any particular candidate. So while overturning Citizens United, and even Speechnow.org, would mark a significant change in Court doctrine, it wouldn’t do all that much to alter campaigns. Both cases were only decided in 2010. Does anyone think money didn’t matter in campaigns before 2010?

In addition to Citizens United, a progressive Court majority would likely, at the earliest opportunity, reverse McCutcheon and Bennett. But McCutcheon affects only a small number of very wealthy donors, who could simply shift their efforts to independent spending, where it is harder to track. Reversing Bennett would assist legislators in designing government financing systems for campaigns, but the reality is that they have experimented with government financing systems nationally and in the states for decades, and they have never proved very effective, nor very popular with the public.

The question, then, is: Would the Court go further and overturn Buckley’s protection of independent expenditures and of ads that do not “expressly advocate” for the election or defeat of a candidate. Buckley has now been the campaign-finance lodestar for more than 40 years. Would a new, progressive majority overturn that precedent?

Though none have explicitly said they would do it, assume that Justices Ruth Bader Ginsberg, Sonia Sotomayor, Elena Kagan, and any newly appointed justice would in fact be prepared to overrule Buckley and vote to uphold spending limits. Then what? At that point, the issue would depend on Justice Stephen Breyer. Assuming that he, too, would agree that spending limits should be constitutional, he would still need to overturn the Buckley precedent.