Was Libby given a Miranda-Tempia warning before he was questioned? If so, what was he told he was suspected of committing? If he was not warned then is his testimony admissible? If he was warned what was he asked about the suspected crime.
Much of what we read implies that he was asked a lot of unconnected questions about a lot of his activities and the inconsistencies in his responses became fodder for the eventual perjury charges... Kafkaesque indeed.
The Libby indictment proves how easy it is for a prosecutor to get an indictment. If Fitzgerald had a chance to prove that Libby was guilty of violating the disclosure of a covert agents identity law, he certainly would have done so.
He he concluded that he could not prosecute under charges that prompted the original investigation he should have dropped the whole thing. Even on the perjury angle he does not have anything approaching DNA on the dress quality evidence.