WASHINGTON — The U.S. Supreme Court “squandered an opportunity” to revise its landmark Citizens United decision when it struck down a Montana campaign finance law on Monday, U.S. Rep. Keith Ellison said.

The court’s ruling on Arizona’s immigration law is getting bigger headlines, and its Thursday decision on President Obama’s health care reform law is much more highly anticipated. But its 5-4 decision Monday to summarily dismiss a case concerning a Montana law banning campaign contributions by corporations is a blow to those advocating for less corporate money in politics, Ellison, a Democrat, among them.

The court overturned a 1912 Montana law banning corporations from spending money on political campaigns. The court’s five conservative justices wrote “there can be no serious doubt” that the 2010 decision in the Citizens United v. FEC case applied to state laws like Montana’s, and declined to hear oral arguments in the case. In essence, the justices ruled they were not interested in revisiting Citizens United.

Citizens United allowed corporations and labor unions to spend unlimited money on political races. Ellison and his Congressional Progressive Caucus have slammed the ruling, and Ellison has introduced a constitutional amendment meant to ban such spending.

A statement from Ellison and fellow CPC co-chair Raul Grijalva (D-Ariz.) read, in part:

“This ruling compounds the damage to our democracy already done by the Citizens United v. FEC decision, which has allowed millions of untraceable dollars to overwhelm our federal, state, and local elections.

“The precedent set by that decision and reaffirmed today allows outside groups to trump popular state and federal laws that keep elections in the hands of the people. …

“We’ve seen this same story all over the country, and we know what happens next. Wealthy donors, corporations and special interests will now have unchecked influence over Montana’s political process. Citizens United is rapidly eroding the foundation of our democracy. The decision announced today is a squandered opportunity to repair that damage.”

A more thorough breakdown of the court’s ruling today can be found here.

Devin Henry can be reached at dhenry@minnpost.com.