In an “industry guidance” document it issued in 2001, the commission said that in deciding whether to punish a broadcaster with fines or license revocations, it would consider “whether the material dwells on or repeats at length descriptions of sexual or excretory organs or activities.” That document said that “the full context in which the material appeared is critically important.”

The approach changed soon after that, when the NBC broadcast of the 2003 Golden Globe Awards drew complaints for the expletive that the singer Bono used as an adjective to express his delight at receiving an award for best original song. The commission overruled its own Enforcement Bureau, which had denied the complaints on the basis of the existing policy, and found that the fleeting expletive fell within the definition of indecency, because it “invariably invokes a coarse sexual image” that made its broadcast “shocking and gratuitous.”

The commission did not impose a penalty against NBC, because the network “did not have the requisite notice” of the new approach, the commission said in its “Golden Globe Awards Order” in 2003.

Complaints about two other broadcasts, of the Billboard Music Awards on the Fox network, eventually led to the case the justices accepted Monday. The entertainers Cher, in receiving an award, and Nicole Richie, in presenting one, both used common expletives that generated complaints. Once again, the commission did not impose a sanction, but it made the new policy official and put broadcasters on notice there would be future penalties. A coalition of broadcasters challenged the new policy in the United States Court of Appeals for the Second Circuit, in New York, raising constitutional and statutory objections.

In a 2-to-1 ruling last June, the appeals court did not address the First Amendment challenge directly. Rather, it held that the commission had violated ordinary principles of administrative law by making “a dramatic change in agency policy without adequate explanation.” The appeals court vacated the commission’s order, instructing the F.C.C. to “articulate a reasoned basis for this change in policy.”