The "sources" are completely irrelevant from a legal perspective. Valerie Plame was not a covert agent. Noone "outed" her. The only relevance of the sources is political.
If Joe Wilson is the "source" everyoone will be aware that this was a political setup by the left.
'Ere now! I bloody well DID NOT! What is it with you lot, always blaming me for everything? It's enough to make a man become a Hermit, it is!