[title should say neccessary - can't change it or links will be ruined]
Is it moral to torture someone if that torture will serve a greater good? What if you do not know whether it will serve any good or not? In a general war, the answer must be absolutely not. To take away the human dignity of another is to lose one's own. But in this new war on terrorism, the answer must change.
As opposed to most wars, where an average soldier has little to no information of military plans (certainly not of something similar to a terrorist attack; most attacks in a regular war are directed toward the opposing military, not civilians in general), terrorists are generally from smaller pockets which tend to know more about each other's actions. A larger problem is that there is a need to find out just who the terrorists are in this case: As opposed to a regular war, in which a country is fighting another country, and therefore is able to determine who is an enemy soldier and who is not, such is not the case here. The only way to determine who the terrorists are is through information - information which only the terrorists can give us.
When I was in Israel two years ago (I studied there post-high school for two years), there was an incident where the Shin-Bet grabbed a terrorist who was about to blow himself up on a Rechov Bar-Ilan, a main street in northern Jerusalem. They interrogated him quite harshly in front of many people, and within minutes they had the answer they needed. They then stopped another terrorist on the other side of Jerusalem, also wearing a bomb vest aimed to kill civilians.
This is the largest difference between a standard war and a war on terrorism. It is not so much that they are not wearing uniforms - it is that they are impossible to differentiate from the standard population without information; that they attack civilians; and that it is almost impossible to predict where they will strike next - they often do not have a strategic goal beyond murder when they attack. People often question whether it is moral to sacrifice the civil rights of one person for the sake of another. In this case, the answer is simple: When someone is dedicating their life to the violation of the civil rights of others, to the murder of people by means of terrorist atrocities, and e fortiori if they are doing so by 'sacrificing' their lives, they have forfeited any civil rights they may have had. "Torture" in this case is not just legal - sadly, it is a moral necessity for society to exist.