No recent decision of the Supreme Court has been more reviled than the 2010 Citizens United decision, which held that the First Amendment prohibits the government from barring corporations and unions from spending money on political communications.

That decision did not produce the result its opponents feared: that Fortune 500 companies would use their corporate treasuries to dominate elections. Instead, it led to the emergence of Super PACs: special non-profit corporations designed to engage in independent political communications — mainly to run TV ads for and against candidates.

Being formally independent of the actual candidates and their campaigns, these Super PACs can accept unlimited donations. A few multimillionaires and billionaires already have given huge sums of money to the Super PACs, which then have produced and run ads supporting their favored candidates and opposing others.

The U.S. Supreme Court signaled last weekend that it may revisit the Citizens United decision, when it announced that it would not allow a Montana campaign finance law to take effect while it considers whether to hear the case on appeal.

The Montana law was a sort of protest against Citizens United: It would have banned corporate expenditures on political communications in state elections. Lower courts in Montana invalidated the law, saying that it was inconsistent with Citizens United. The Montana Supreme Court disagreed.

In effect, they argued that circumstances and facts specific to Montana justify different regulations than are appropriate for national elections.

Had the U.S. Supreme Court simply issued an order staying the operation of the Montana decision until it decided what to do, it would have attracted little notice.

But Justices Ruth Bader Ginsburg and Stephen Breyer added a statement, suggesting not only that they would like to see Citizens United reargued, but also indicating the line of argument they would like to see the litigants develop.

They make it clear that they reject the effort to draw a distinction between the circumstances of Montana and circumstances in the rest of the country. Instead, they see the Montana case as an opportunity for reconsidering the constitutionality of campaign finance regulations.

They wrote that, “Montana’s experience, and experience elsewhere” since 2010 “make it exceedingly difficult to maintain that independent expenditures by corporations do not give rise to corruption or to the appearance of corruption,” adding that they would like the court to consider “whether, in light of the huge sums currently deployed to buy candidates’ allegiance, Citizens United should continue to hold sway.”

Since restrictions on donations to Super PACs and restrictions on expenditures by such groups would reduce the number of political advertisements and thus the amount of political “speech,” there is at least a potential conflict between such restrictions and the First Amendment, which holds that “Congress shall make no law… abridging the freedom of speech.”

When faced with a law that limits “speech,” the court does not always decide in favor of freedom. If the government has a very good reason for limiting speech, and if the restriction is the only way to do what the government has very good reason to do, the law is upheld.

The big issue arising in the wake of Citizens United, and the issue Justices Ginsburg and Breyer would reopen, is whether the enormous donations individuals can now make to the Super PACs pose such a danger to the integrity of our elections that the government is justified in prohibiting them and thus in restricting the “speech” that such donations underwrite.

At bottom, this should be an empirical question. Can the government show that the people who write million-dollar checks to promote candidates and ideologies get special favors or special treatment they would not have gotten under more restrictive campaign finance rules?

If it can, the case will be easy, but if it could show quid pro quo favoritism, it could probably prosecute the donors for outright bribery.

Indeed, the more money individuals spend to support candidates the harder it will likely be for elected officials to reward them, because great expenditures will invite great scrutiny.

The court might decide that big expenditures “appear” to cause corruption, and that the government should ban such donations to preserve appearances, but it is unlikely to do so, because it is hard to see why the government should limit speech in the absence of identifiable, demonstrable harm.

The liberal remedy for speech we don’t like should be more speech, and we should remain confident in the integrity of our elections as long as the vote remains, as it should be — priceless.

Joseph R. Reisert is associate professor of American constitutional law and chairman of the department of government at Colby College in Waterville.