The first anniversary of the Supreme Court’s decision to roll back longstanding bans on corporate campaign contributions has spawned calls to reopen the ruling.

A collection of campaign-finance reform advocates has organized events around the country to protest the high court’s decision in Citizens United vs. the Federal Election Commission, which opened the spigots for corporate campaign contributions in the run-up to the 2010 midterms.

The most aggressive of these protests is from Common Cause, which has asked Attorney General Eric Holder to investigate whether two Supreme Court justices should have recused themselves from the case.

Common Cause says that Justices Antonin Scalia and Clarence Thomas have close ties to groups that directly benefited from the decision, and cite their attendance at fund-raising retreats organized by a pair of conservative activists who spent millions in the last election.

If the attorney general finds evidence that the justices were conflicted, Common Cause is asking Mr. Holder to petition Chief Justice John Roberts to vacate the Citizens United decision…