Popping in for one more observation (and I haven't caught up with every post, so I apologize if I repeat someone):
In my eyes, the key question here is how extreme you are in your view of evil. Again, I can only speak for Eberron, and in Eberron the goal is to play with shades of gray and to say that there is a lot of evil in human nature... that if anything, good is the greater rarity, making the good hero truly stand out.
If you say that evil alignments should be reserved for the truly horrific and extreme - unrepentant rapists, serial killers, and actual demons - then of course that's not Jack. However, if this is the case, I don't see how it would be remotely feasible to encounter evil people in a world with the magical sophistication of Eberron or the Forgotten Realms. If evil people are reliably that bad - if you know that an evil person is automatically on par with a baby-murderer - then you should have goverment-mandated teams of paladins and clerics rooting out all people of evil alignment for the good of society. Essentially, you'd end up with Minority Report: you may not have done anything, but since only absolutely vile beings show up as evil, your alignment alone is good enough for us to bring you down. In my mind, this would create a very alien society, and one without much excitement for adventurers, because evil has been burnt out of the world.
Hence, I broaden the range of evil, to include the slumlord who cuts corners to make a profit even though he knows it's threatening the lives of his tenants; the government agent willing to torture in the name of his country; the general who authorizes massacres to demoralize an enemy. The general may actually end the war more swiftly through his actions, and in the long run, save lives. The spy may get information vital to the survival of his nation. And the landlord... well, he's just scum, but that's business. You don't like the way he does things, earn your own gold and build your own #%$@ house.
With this in mind, detect evil becomes a tool that tells you something about someone's character, but it doesn't tell you everything. It tells you they are comfortable with some evil acts, but not the circumstances or what evil acts. That evil government agent would think the slumlord was scum... and unlike a good character, who might try to see the slumlord brought to justice (if lawful) or force him to compensate his victims outside the law (if not), the evil agent might simply kill him, or for that matter torture him to teach him a lesson. You can't arrest every person of evil alignment if a third of the world is evil - and if many evil people don't actually take actions that harm innocents. Again, take the bloodthirsty barbarian who only fights because he loves to inflict pain on others... and yet, who is fighting invading demons. The barbarian's an evil man, but his aid may be just what you need. However, if he turns on innocent villagers, you'll have to bring him down. Detect evil tells you what he's capable of - that he isn't acting out of any sense of altruism or empathy for others, that he's potentially capable of truly vicious and ruthless acts - but it doesn't tell you about his blood oath to destroy demons, the vow he took that fuels his vendetta against them.
In Eberron, this is why the Church of the Silver Flame doesn't fight "that which is sensed by detect evil" - it fights those who threaten the innocent. It fights evil in the world with the sword, and seeks to redeem evil in the mind through guidance.
So when I say I see Jack Bauer as evil, it's because I think that by *my* standards, a lot of government agents have to be evil to do their job efficiently... and that this doesn't make them monsters, it makes them people with certain views of ethics, empathy, and the sacrifices that must be made in the name of their cause. Essentially, in Eberron I advocate narrowing the definition of neutrality and expanding the spectrum of both good and evil. If you'd call someone "neutral with evil tendancies" - just make 'em evil. There is a huge difference between Hannibal Lecter and Jack Bauer, but I'm comfortable making both evil. Fuzzing this line makes it more difficult for detect evil to be the be-all end-all in villain detection and allows more mystery in the world. When you discover the Dark Lantern working with you is evil, you know to keep an eye on him... but you can't automatically assume that means he's going to betray you. He may simply be ruthlessly devoted to his nation.
With all that said, I also feel strongly that people can perform actions outside of their alignment under duress: alignment is a guideline, not a chain. Repetition and comfort is the key. As such, I agree that in Jack, we may be seeing a gradual change in alignment, as he is forced to become more comfortable with extreme methods. And in response to the question of "So in some of the torture situations, what alternative did Jack have?" - he had the choice not to take the actions that he did, actions often challenged by his compatriots. Yes, if he didn't do what he did, hundreds of people might have died. But a good-aligned person - like the people who challenged him - might still hesitate to take the ruthless action, even though it resulted in greater disaster. As I said, I believe that many governments would (or do) employ evil people for precisely this reason.
So, it all comes back to your view on evil. Mine is that evil is a part of human nature and a part of our world, not something that can be excised... because if it was reserved for truly extreme and horrible cases, a world with the ability to detect evil would take action to eliminate it. Following these principles, I would make Jack evil... a good man who has fallen into evil, but who is still bound by his loyalty to his nation and family, and by his personal integrity. An evil person serving a good cause, and who only engages in evil actions because he feels those actions are necessary. Essentially, I believe that both good and evil people can be heroes... or, for that matter, villains. Alignment shapes your methods, but does not automatically define your loyalty or your goals.
