Has anything changed in the world of campaign finance that might give pause to the five members of the Supreme Court who decided Citizens United v. Federal Election Commission exactly 28 months ago Monday?

Or, to be more precise, has anything changed in the mind of at least one of them?

The court faces that question in a flurry of contradictory arguments prompted by a decision by the Montana Supreme Court late last year.

In upholding a 100-year-old state law, the Montana justices seemed to be openly defying Citizens United’s holding that the First Amendment grants corporations, and by extension labor unions, the right to spend unlimited amounts of their treasuries to support or oppose candidates.

The Supreme Court has already blocked the Montana decision, and the justices may simply set their counterparts in Helena straight by summarily reversing the finding.

But pressure is being applied — by members of Congress and nearly half the states, not to mention Justices Ruth Bader Ginsburg and Stephen G. Breyer — to at least let Montana make its argument.

The Montana Supreme Court acknowledged a conflict when it voted 5 to 2 to uphold the state law, created by voters in 1912 to combat the power of the so-called Copper Kings who controlled state politics. It said the state’s characteristics, including a dependence on agriculture and mining and low campaign costs, made it “especially vulnerable” to corporate control.

Those urging the court to grant a full hearing of the Montana case take aim at the most important finding of Citizens United. That was the declaration in Justice Anthony M. Kennedy’s majority opinion that “we now conclude that independent expenditures, including those made by corporations, do not give rise to corruption or the appearance of corruption.”

“That cannot be so,” the new bipartisan team of Sens. John McCain (R-Ariz.) and Sheldon Whitehouse (D-R.I.) told the court. “Whether independent expenditures pose dangers of corruption or apparent corruption depends on the actual workings of the electoral system; it is a factual question, not a legal syllogism.”

The court under Chief Justice John G. Roberts Jr. has incrementally undermined McCain’s landmark campaign finance act by saying it doesn’t meet First Amendment requirements. McCain has in turn been dismissive of a court — without a single member who has ever run for public office — that he says is hopelessly naive about how campaign finance affects the political process.

Groups that favor campaign finance restrictions say lower courts have misinterpreted the meaning of Citizens United to allow the rise of super PACs that are simply auxiliaries of candidates. They add that the FEC has been hapless in providing the kind of contribution disclosures that the Supreme Court acknowledged were necessary for an informed electorate.

Today’s political action committees are “wholly distinct from the organizations this court has seen in the past,” the Brennan Center for Justice told the court in its amicus brief.

Those on the other side say opponents of Citizens United border on hysterical.

“From the day it was issued, this court’s ruling in Citizens United has been the subject of sustained, overheated, and sometimes irresponsible attack,” says a brief filed for Senate Republican leader Mitch McConnell (R- Ky.) by noted First Amendment lawyer Floyd Abrams.

“This is hardly the first time in the court’s history that its application of one or another of the provisions of the Bill of Rights has led to such commentary,” it adds.

The brief contends that the concerns of dissenting justices — as well as President Obama — that corporations would take over all aspects of campaign finance have not been realized. More than 86 percent of the nearly $100 million spent by the eight super PACs linked to Republican presidential candidates, the brief said, came from wealthy individuals whose role in campaign finance has been blessed by the court since 1976.

And what has the money gone for? Ads that have criticized Mitt Romney for taking contradictory positions on public policy questions and questioned whether Newt Gingrich would be an effective standard-bearer for the party.

“They are, as would be expected, pure political speech of the sort that the First Amendment most indisputably protects,” the brief states.

Those are just previews of the arguments that will be made should the court decide to take the Montana case for a hearing next term. Ginsburg and Breyer already made clear they think the court should take the opportunity to “consider whether, in light of the huge sums currently deployed to buy candidates’ allegiance, Citizens United should continue to hold sway.”

It takes four justices to agree to hear the case. Justice Sonia Sotomayor signed on to the scathing 90-page dissent to the Citizens United decision by Justice John Paul Stevens, now retired, and Justice Elena Kagan unsuccessfully argued the case when she was Obama’s solicitor general.

But it is not clear whether Ginsburg and Breyer would force their still relatively new colleagues to relive the Citizens United case if they believed the outcome would be the same.