UPDATE-   Check out this piece by Tom Goldstein on the Montana case from SCOTUSblog (thanks to Rick Hasen’s Election Law Blog)

The Supreme Court of the United States has entered a stay of the Montana Supreme Court‘s determination that the century-old Montana Corrupt Practices Act was necessary to prevent corruption of state elections by corporate spending. In taking the action based on its decision in Citizens United v. FEC, the Supreme Court did not examine the substantial factual record in the Montana case or give the State a hearing. Nevertheless, the Court will decide whether to allow a petition for certiorari and may consider the case further.

In an extraordinary criticism of a case decided only two years ago, Justice Ginsburg, joined by Justice Breyer,  took the opportunity to call for a re-examination of Citizens United:

Montana’s experience, and experience elsewhere since this Court’s decision in Citizens United v. Federal Election Comm’n, 558 U.S.  __ (2010), make it exceedingly difficult to maintain that independent expenditures by corporations “do not give rise to corruption or the appearance of corruption.” Id., at __ (slip op., at 42. A petition for certiorari 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 Montana Supreme Court had cited the state’s demonstration of corruption caused by corporate spending in elections, and the effect of Montana law in preventing that corruption, as a reason to distinguish the state’s law from the federal Bipartisan Campaign Reform Act struck down in Citizens United.

Here’s the Supreme Court’s Order.