An appeals court on Tuesday reversed a lower court ruling that likely would have led to greater disclosure of who is paying for certain election ads.

In March, U.S. District Judge Amy Berman Jackson ruled that the Federal Election Commission overstepped its bounds in allowing groups that fund certain election ads to keep their financiers anonymous.

But Tuesday's unanimous ruling by a three-judge panel of the U.S. Court of Appeals for the District of Columbia sent the case back to Jackson, with instructions to refer the matter to the FEC for further consideration.

At issue are electioneering communications — ads that don't expressly advocate voting for or against a candidate running for federal office. In 2007, the FEC ruled that only contributors whose donations were "made for the purpose of furthering electioneering communications" had to be identified; those who gave unrestricted money did not have to be identified. The FEC regulation came in response to a Supreme Court ruling that gave more latitude to nonprofit groups — like the Karl Rove-backed Crossroads GPS and the President Barack Obama-leaning Priorities USA — on pre-election ads.

Rep. Chris Van Hollen, D-Md., sued the FEC over the regulation, which he called a "loophole" that made the disclosure requirements meaningless. He won a summary judgment from Jackson, who was appointed by Obama. The judge ruled that "Congress spoke plainly" in passing the McCain-Feingold campaign finance law — and did not delegate authority to the FEC to narrow the disclosure requirement.