On Sunday, while interviewing National Security Adviser Tom Donilon about the killing of Osama bin Laden, Fox News Sunday host Chris Wallace asked: “Why is shooting an unarmed man in the face legal and proper while enhanced interrogation including waterboarding of a detainee under very strict controls and limits, why is that over the line?” Fox News has since promoted this as possibly the best question ever asked.

But in fact, common sense provides an answer to Wallace's question. For a moment, let's take terrorism out of the equation and look at two cases of alleged police brutality in New York City: the cases of Amadou Diallo and Abner Louima.

Diallo, a resident of the Bronx, was stopped early one morning in February 1999 by New York City police officers looking for a serial rapist. During the stop, Diallo reached into his jacket. The officers said they thought Diallo was reaching for a gun. They fired 41 shots, hitting Diallo 19 times and killing him. It turned out that Diallo was unarmed and had been reaching for his wallet. After a trial, the officers were acquitted of all charges resulting from Diallo's death.

While some disagree with the outcome of the Diallo case, it's obvious that if police officers can show a reasonable fear that a civilian is threatening them, they can respond with force (including deadly force if appropriate).

Louima, a resident of Brooklyn, was arrested by New York City police officers who were responding to a disturbance at a Brooklyn nightclub. One of the police officers believed that Louima had punched him during the disturbance. Louima then was sodomized in a bathroom of the police precinct by police officers. Two of the police officers involved in the case were convicted of charges arising from the Louima case. And no one would dispute that, if Louima's allegations were true, the officers involved committed a crime.

But recall that Louima's ordeal started because an officer believed Louima had attacked him. Therefore, as we know from the Diallo case, the use of force (and perhaps even the use of deadly force) might have been justified in arresting Louima. That doesn't mean, however, that the officers had a free pass to torture Louima later. In other words, just because the police might be able to legally kill someone at one point, it doesn't mean the police are allowed to torture that person under different circumstances.

Of course, there are major differences between Diallo and Louima on the one hand and bin Laden and the Al Qaeda detainees subjected to waterboarding and other enhanced interrogation techniques on the other. Unlike bin Laden, Diallo was an innocent man whom the police were not even in the process of arresting when they killed him.

Louima is also very different from the detainees who were waterboarded. First of all, the detainees who were waterboarded were members of Al Qaeda, not people who may have been involved at a disturbance at a nightclub. There was also no even arguable reason for the police to torture Louima. And Louima's torture did not occur under any controls and limits.

Nevertheless, the basic point is valid: It is sometimes legal to shoot someone while trying to apprehend or even just talk with that person, but that does not mean that it is legal to torture that person once you have him or her in custody and at your mercy.