As a military intelligence officer in the Mekong River Delta region of Vietnam in the late 1960s, where U.S. forces battled both the North Vietnamese Army and the Vietcong, Chris Walters had no trouble identifying enemy soldiers.

They were the ones who were shooting at you.

It was Walters' job to find out where the enemy stored munitions, what they had in the way of defenses, and what their battlefield plans were. The people Walters interrogated had been picked up following shoot-outs or had been pulled out of bunkers stuffed with weapons.

So when the opportunity emerged a few years ago for Walters, by then a senior litigator at Reed Smith, to represent Guantanamo detainees, he and a handful of other lawyers with military backgrounds jumped at the chance.

Because many of the detainees had not been picked up on the battlefield, but rather on information from paid informants, the basis for the confinement of at least some of them was questionable, Walters reasoned.

Just as compelling was the fact that the detainees had no means of challenging their imprisonment.

In effect, Guantanamo had become a legal black hole.

"We were not dealing with left-wing tree huggers here," Walters said of the Reed Smith lawyers who represented Guantanamo inmates. "We were talking about military combat leaders."

Since the prison camp opened Jan. 11, 2002, about 850 lawyers from 120 private firms, including the nation's biggest and most prestigious, have represented the detainees, according to the Center for Constitutional Rights, a liberal advocacy group that helped coordinate the legal strategy.

In Philadelphia, firms providing legal services to Guantanamo prisoners, sometimes in the face of resistance from commercial clients, include not only Reed Smith, a Pittsburgh-based mega-firm with a 150-lawyer office in Center City, but also Dechert L.L.P., Ballard Spahr, and Hangley Aronchick Segal & Pudlin P.C.

In what has become the great circus of American political discourse, the Guantanamo prison camp is an ideological Rorschach test: Depending on your politics, the detainment of hundreds of accused al-Qaeda and Taliban fighters at Guantanamo in the aftermath of the Sept. 11, 2001, attacks constitutes either a massive human-rights abuse or a necessary means for protecting the nation from attack.

The reality is somewhat more nuanced.

In fact, for all the vilification of President George W. Bush's response to the 9/11 attacks, there were persuasive political and national security reasons for an aggressive American response.

The climate of fear in Washington following the hijackings and then the bizarre anthrax killings was palpable. For more than a year following the attacks, there were regular media reports that al-Qaeda militants, though they may not have acquired nuclear weapons, might set off a so-called dirty bomb, a crude explosive device containing radioactive material that, when spread by the explosion, could make downtown Washington or Manhattan uninhabitable for generations.

The anxiety level in Washington was so high that some people were selling their houses based on the idea that it was only a matter of time before the town was nuked.

And yet to lawyers such as Walters, who coordinated the Guantanamo representations at Reed Smith, there needed to be limits to what the U.S. government could do in the name of national security.

After all, even Lincoln was challenged after he had suspended the writ of habeas corpus, the guarantee under law that people who are arrested can challenge their confinement, during the Civil War.

Part of the attraction was that the issues surrounding Guantanamo composed a legal terra incognita. The circumstances of the attack, by a shadowy network of stateless terrorists with operations that came close to spanning the globe, were unprecedented.

The enemy was apprehended not only on the battlefields of Afghanistan but in alleged al-Qaeda safe houses in Bosnia.

In establishing a prison camp at the American naval base in Guantanamo, the Bush administration had created a detention center where prisoners theoretically were beyond the reach of not only the Geneva Conventions but also the U.S. Constitution. From the start nearly 800 prisoners have been held there; the number now is fewer than 200.

"It was always clear [in earlier conflicts] that you were holding an enemy combatant," said Walters, 67, a graduate of Princeton and Michigan Law School. "In this Guantanamo situation, anyone who understood the situation knew that we were holding a bunch of guys who had been mostly handed over, not captured."

In 2008, the U.S. Supreme Court largely agreed. In Boumediene v. Bush, Justice Anthony Kennedy, the court's center-right swing vote, wrote in a majority opinion that prisoners of war held in what was effectively a U.S. jurisdiction must have some minimum process to challenge their detention. (Read the suit at

Critics of the Guantanamo legal assault asserted early on that if the detainees had a right to habeas corpus, it wouldn't be long before U.S. soldiers were reading Miranda rights to captured soldiers on the battlefield.

But as University of Pennsylvania law professor Kermit Roosevelt notes, Boumediene does nothing of the kind. In this context, the U.S. Constitution applies only in places under control of the U.S. government.

"Boumediene really turns on the unique status of Guantanamo as a place under complete U.S. jurisdiction and control," Roosevelt said.

Even so, representation of Guantanamo prisoners has been a politically sensitive issue for some firms. Walters said he had concerns initially about criticism from clients and lawyers.

But the firm's management committee signed off on the representation within a day after Walters and two lawyers in the firm's Washington office, Douglas Spaulding and Bernie Casey, made the proposal. One client did object but dropped the matter after Walters explained the underlying issues.

In the end, the vast majority of Guantanamo inmates were released without hearings. Peter Ryan, a commercial litigator who represented a group of 16 Guantanamo detainees while he was a lawyer at Dechert before he moved to Cozen O'Connor earlier this year, says 11 of the detainees already have been released by the Pentagon without explanation. One, a tribal leader who was picked up based on the word of an informant, now is running for public office in Afghanistan.

Ryan is not sure his representation had any impact, but he says it was important for Americans to establish some minimal procedure for separating real combatants from others who had been mistakenly picked up.

"It was a simple process question, the idea of having a neutral decision-maker decide whether the facts and the law supported" the detentions, Ryan said.

For lawyers like Walters and Ryan, after all the legal debate and maneuvering, that was the basic point. Prisoners who faced endless confinement in what seems to be a never-ending war on terror ought to have some means to show why perhaps they should be freed.

For these lawyers, it is a concept that has nothing to do with politics and ideology - and everything to do with the law.