In a decision that might have implications for the drive to improve Arkansas ethics law, the U.S. Supreme Court today reversed a Montana Supreme Court ruling upholding that state’s ban on independent corporate spending on political races.

It was 5-4 — with Breyer, Kagan, Sotomayor and Ginsburg.

The question presented in this case is whether the holding of Citizens United applies to the Montana state law. There can be no serious doubt that it does. See U. S. Const., Art. VI, cl. 2. Montana’s arguments in support of the judgment below either were already rejected in Citizens United, or fail to meaningfully distinguish that case.

I’ll have to read further to see how this thinking squares with federal law, which was undisturbed by Citizens United and prohibits direct corporate contributions to federal candidates. This ruling, too, appears only to relate to independent spending by corporations. Montana banned it entirely, but it also banned direct contributions to candidates and that ban was upheld by lower courts and not mentioned in today’s brief Supreme Court reversal.

The pending Regnat Populus 2012 initiative on Arkansas ethics reform would ban direct corporate contributions to Arkansas political candidates, though not prevent corporations from making PAC contributions or from making independent expenditures. I need to gather some opinion on whether today’s ruling has an impact on that, but I don’t believe this ruling imperils that provision in the Arkansas proposal. The dissent does note that independent expenditures aren’t much different than direct ones to a candidate.

As Justice Stevens explained, “technically in­dependent expenditures can be corrupting in much the same way as direct contributions.” Indeed, Justice Stevens recounted a “substantial body of evidence” suggesting that “[m]any corporate inde­pendent expenditures . . . had become essentially inter­changeable with direct contributions in their capacity to generate quid pro quo arrangements.”

Common Cause says the time is night for a push for a constitutional amendment to overturn the court’s ruling of unfettered corporate influence.

The court’s curt reversal turned aside arguments that peculiar circumstances — such as pervasive corporate corruption historically in Montana — might support different standards in the states.

UPDATE: Here’s a full explanation of where things stand on direct corporate contributions to candidates. Still OK to make them illegal. But a case is working through the courts attempting to knock that down, too.