Bottom line is there was no proof, just interpretations of what someone remembered or did not and whether or not there was criminality in the intent.
IMO completely impossible to prove and was proved to not be pertinent to the issue of outing Plame at all since she was never covert.
Fitz should have wrapped this up by day #3.
The minute Libby's defense team started to try to blame Cheney as opposed to blaming WILSON and PLAME for "outing themselves," he was screwed. I didn't understand that stupid line of defense from the get-go.