"But what has seemingly escaped the appreciation of the press and pundits is the fact that the FEC must still articulate a rule that comports with the statute. You know, that law that Congress passes, which then is codified in the United States Code (as opposed to the law of hypothetical terms sewn together in the dreams of men). To paraphrase former defense secretary Donald Rumsfeld, the FEC goes to war with the statute it has, not the statute it would like to have. To be sure, it doesn't make life easier that the interpretation of that statute must comport with the Supreme Court's various constitutional rulings—but that's no excuse to ignore the statute.
Those of you lawyers out there may recall (from Con. law or Admin. Law) that administrative agencies can promulgate interpretations of statutes, but lack the power to 'write new law.' Once we swallow this principal, I think the dust-up over the Citizens United rulemaking gets a lot less perplexing."
Why the frown at the FEC? Allison Hayward explains why the FEC isn't Congress...
Center for Competitive Politics: