The media covere it ass by claiming Plame had already been outed:

THE MEDIA TELLS THE COURT: PLAME'S COVER WAS BLOWN IN THE MID-1990s
As the media alleged to the judges (in Footnote 7, page 8, of their brief), Plame's identity as an undercover CIA officer was first disclosed to Russia in the mid-1990s by a spy in Moscow. Of course, the press and its attorneys were smart enough not to argue that such a disclosure would trigger the defense prescribed in Section 422 because it was evidently made by a foreign-intelligence operative, not by a U.S. agency as the statute literally requires.

THE CIA OUTS PLAME TO FIDEL CASTRO
Of greater moment to the criminal investigation is the second disclosure urged by the media organizations on the court. They don't place a precise date on this one, but inform the judges that it was "more recent" than the Russian outing but "prior to Novak's publication."

The press informs the judges that the CIA itself "inadvertently" compromised Plame by not taking appropriate measures to safeguard classified documents that the Agency routed to the Swiss embassy in Havana.