Scott Johnson at Power-Line deservedly cites as definitive Andrew McCarthy’s column at NRO: Say “No” to the McCain Amendment, which eloquently, and unanswerably, concludes:

We should be asking this question of each and every member of Congress who claims to support the McCain Amendment: If we had credible information regarding an ongoing al Qaeda plot to detonate a nuclear weapon in the continental United States, and we had just taken into custody an al Qaeda militant who was in a position to know where and when the attack was to occur but who was refusing to cooperate, are you saying we would need to let thousands of Americans die rather than harm a hair on the terrorist’s head in an effort to extract the information that might save them?

If the answer to that question is “no,” you have no business voting for the McCain Amendment. If the answer is “yes,” you have no business serving in a government whose first obligation is the security of the governed.