That Romney film

Dominating the South Carolina Republican primary election campaign is the attack documentary film, “When Mitt Romney Came to Town.” Excerpts are running on television almost nonstop. It is either scurrilous or persuasive — and maybe both. Judge for yourself. You can watch it on YouTube.

We will know after the Saturday vote whether it is helping Newt Gingrich overtake Mitt Romney in the race for the Republican presidential nomination. So it is an important new ingredient in the contest for both politicians.

Perhaps even more important, this expensive film — $10 million for the production and more than $3 million for the TV time — promises to be just the start of a flood of such attacks through this year’s primaries and the general election campaign.

Expensive? Sure, but the U.S. Supreme Court has opened the gates for an unlimited torrent of political contributions by supporters of the various candidates. We will see the enormous effect of the 2010 landmark case, Citizens United v. Federal Election Commission. It was brought by a right-wing group that simply wanted to use its own money to show a film attacking now-Secretary of State Hillary Clinton, then a candidate for the White House.

The Supreme Court’s solid five-member conservative bloc expanded the case in a remarkable instance of judicial activism. The five members, at their own invitation, questioned the constitutionality of long-standing congressional restrictions on political spending by corporations. They threw out the restrictive laws. They also held that corporations must enjoy the same First Amendment rights as people.

The decision opened the way for the growth of super PACs, huge political action committees that can spend without limit in campaigns the money that corporations can now give them without limit. Individuals, too, may contribute without limit to federal PACs, under a decision by the U.S. Court of Appeals for the District of Columbia Circuit, as long as they are “independent expenditures” — not coordinated with a candidate whom they are supporting.

The Romney film and other “independent” support for Mr. Gingrich comes partly from a $5 million check given by a casino mogul, Sheldon Adelson, to a super PAC, Winning Our Future, run by Gingrich supporters. Mr. Adelson has promised millions more. He is reported to be worth more than $21 billion. After critics found some exaggerations and inaccuracies in the film, Mr. Gingrich asked the PAC to stop showing its cuts. But the showing goes on, so Mr. Gingrich has it both ways.

The whole year probably will be awash with political money, living up to the worst predictions of critics of the Supreme Court decision. And Citizens United, which brought the case on behalf of a conservative film, can see an early result in the financing of a liberal or left-wing film, even though produced to benefit the conservative Mr. Gingrich.

If Americans get sick of so much money in politics and so much politics on their TV screens, a remedy is in sight. The liberal watchdog group Common Cause this week launched a 50-state drive calling on Congress to pass a constitutional amendment to reverse the Citizens United decision.

Unlike the “nine old men” who frustrated key parts of President Roosevelt’s New Deal, the five conservatives on the present Supreme Court are relatively young. If Americans decide that the flood of corporate political spending must be halted, a constitutional amendment looks like the best remedy.