I agree with the Bob--the poll is so blunt as to be meaningless. The notion that unethical behaviour (however defined) is tolerable so long as it saves just one American life is silly in the extreme: if overriding human rights is justified on those grounds, you might as well force all American cars to drive below 15mph (to avoid tens of thousands of fatal accidents), ban firearms and sharp implements (ditto), ban alcohol (ack!), and force everyone to wear giant inflatable suits in case they trip over their shoelaces (well, ban those too while you're at it).

Heck, you could probably save far more American lives in the average year by adopting a proper system of socialized medicine than by allowing the intelligence community to have free unethical rein in the war on terror

There are, I think, two sets of issues here:

1) Ethics as a requirement of operational effectiveness. Sometimes the ethical and the effective go hand in hand. Sometimes they don't.

2) Ethics as characteristic of those things that make the US worth defending, as a citizen or as an ally. Frankly, I would be reluctant (as a US ally) to fully cooperate with a US that engaged in systematic violations of human rights as a national interest. If it went the full Syria/North Korea route of systematic use of torture in interrogation, I would probably be inclined to see it as an unfriendly power and act accordingly. Much of the Western world would feel the same.