One likely factor in that calculation is that putting Mr. Libby on the stand would expose him to a cross-examination by
Patrick J. Fitzgerald, the chief prosecutor, that could be withering. Mr. Fitzgerald complained that the defense had engaged in a “bait and switch” tactic by keeping Mr. Libby off the stand after repeatedly suggesting that he would testify.
Mr. Cheney’s testimony, which was much anticipated, would have set a precedent as the first appearance of a sitting vice president as a witness at a criminal trial. It was also expected to bolster a major part of Mr. Libby’s defense: that he was so consumed by the crush of high-stakes issues like global terrorism and Iraq that he might not have remembered all the details of his conversations.
But the trial threw up numerous instances in which Mr. Cheney took a personal role in managing the White House response to accusations from
Joseph C. Wilson IV, a prominent critic of the Iraq war, that the evidence for going to war had been knowingly overstated. Mr. Cheney could have been exposed during cross-examination to uncomfortable questions about his close involvement in trying to undermine Mr. Wilson’s criticisms.