Another One For Comey

Greenwald expands on the discussion of yesterday's Comey testimony like no one can, but there is still something not clear to me. Greenwald says it like this:

Yet even once Bush knew that both Aschcroft and Comey believed the eavesdropping was illegal, he ordered it to continue anyway. As Anonymous Liberal wrote yesterday:

That's a rather stunning fact, and one that I wish at least a few mainstream journalists would attempt to grasp the significance of. The White House authorized a program that everyone of significance in the Justice Department had determined to be lacking any legal basis. They willfully violated the law.

But it is not at all clear to me what the status was prior to this. The administration obviously had the green light before the dramatic rush to Ashcroft's bedside, and I believe that the AG had been signing of on it every 45 days for months and months before that. So what gives? We can agree that the authority and precedent relied upon by the administration (the Yoo doctrine) is loony if not breathtaking, but what caused the abrupt about face in the opinion of the AG and his top brass?