Such suits, known as Bivens actions, are difficult to win. The law affords federal officials immunity from lawsuits when they are acting within the scope of their duties.
The law also requires that the officials know that their conduct affects the exercise of particular constitutional rights. Some legal scholars said it would be hard for Wilson to show that his right to speak out was affected by the decision of Rove and Libby to reveal the CIA affiliation of his wife.
"If you are going to be out there criticizing the government, then the government, just like anybody else, will often try to explain why you are in the wrong. That is part of the public debate," said Eugene Volokh, a law professor at UCLA.
Though Plame's status as an operative was classified, even Fitzgerald did not find that the disclosure broke a federal law protecting covert agents, Volokh said, adding that "not every violation of federal criminal law is a constitutional violation."
But other experts said the ultimate success of the lawsuit, measured in dollars, might be beside the point. They said it would be difficult for the officials to get the suit quickly thrown out, giving Plame, Wilson and their legal team an opportunity to question them under oath and obtain their notes, documents and even statements and grand jury testimony given as part of the Fitzgerald probe.
That could help answer the major unanswered question in the case: the identity of a senior administration official who told Novak about Plame. Novak discussed his role in the investigation this week, but has declined to reveal his main source.
"The key point is that filing the lawsuit will permit Plame Wilson to subpoena witnesses -- such as Robert Novak -- to provide testimony," said John T. Nockleby, a professor at Loyola Law School. "As a result, we may finally learn who is the mystery person who first spoke to Novak."
