Supreme Court Justices Ruth Bader Ginsburg, center, and Stephen G. Breyer, second from right, suggested Friday that the court reconsider its controversial 2010 decision that allowed unlimited corporate and union spending in elections. (Alex Wong/Getty Images)

Two Supreme Court justices suggested Friday that the court reconsider its controversial 2010 decision that allowed unlimited corporate and union spending in elections.

The suggestion came as the court blocked a Montana Supreme Court decision upholding a century-old ban on corporate campaign spending in the state.

The Montana ruling seems squarely at odds with the court’s 5 to 4 decision in Citizens United v. Federal Election Commission, which allowed unlimited corporate spending. The U.S. Supreme Court majority had said such independent spending did not give rise to corruption or the appearance of corruption.

In Friday’s order, Justices Ruth Bader Ginsburg and Stephen G. Breyer said the upheaval in the world of campaign finance since the Citizens United decision does not bear out the majority opinion.

“Montana’s experience, and experience elsewhere since this court’s decision in Citizens United v. Federal Election Commission, make it exceedingly difficult to maintain that independent expenditures by corporations ‘do not give rise to corruption or the appearance of corruption,’ ” Ginsburg wrote.

“A petition for certiorari [from those challenging the Montana court’s decision] will give the court an opportunity to consider whether, in light of the huge sums currently deployed to buy candidates’ allegiance, Citizens United should continue to hold sway.”

The U.S. high court’s action Friday does not necessarily mean that it will hear the Montana case; it could later summarily reverse the Montana court’s decision. There is no timetable for such action, but Friday’s stay probably means that corporations will be able to spend money on state and local races in Montana this year.

In Friday’s order, Ginsburg appeared to refer to the vast amounts of money spent by super PACs that have flourished in the aftermath of Citizens United and subsequent decisions by lower courts and the FEC.

Corporations and wealthy individuals have contributed millions of dollars to super PACs supporting individual candidates for the Republican presidential nomination. Altogether, super PACs have spent twice as much on television advertising as have the candidates’ campaigns, according to estimates by Kantar Media/CMAG, an ad tracking firm.

The Montana court’s action has given rise to the first challenge of the Citizens United decision. By a 5 to 2 vote, the state court upheld Montana’s 1912 Corrupt Practices Act, which prohibits certain political spending by corporations.

The Montana court acknowledged the conflict with Citizens United, but Chief Justice Mike McGrath said the state was especially vulnerable to “continued efforts of corporate control to the detriment of democracy and the republican form of government.”