WASHINGTON (CNN) -- Prescott Prince is a small-town lawyer who has never taken a death penalty case to trial. Yet he finds himself involved in one of the biggest capital punishment cases this century: He's defending the alleged mastermind of the September 11 terror attacks, Khalid Sheikh Mohammed.

Prescott Prince says the suspected 9/11 mastermind deserves a fair trial.

He readily acknowledges how his client is perceived as "one of the most reviled people" in the world. But he says it's imperative that America give Mohammed a fair trial, just like anyone else accused of a crime.

No civilian court, he says, would accept confessions obtained after a defendant was mistreated. But the CIA admits Mohammed was waterboarded, a controversial interrogation technique that involves simulated drowning.

"I take the position that this is mock execution. ... Colloquially speaking, at least it's torture," Prince said.

The fact that whatever Mohammed said during such duress could be used at trial is alarming to Prince.

"That's not the rule of law. That's just insanity." Watch waterboarding is "mock execution" »

A Navy reservist who has been called to active duty, Prince, 53, rejects the suggestion that he is less than patriotic for representing an accused terrorist. "I had friends who were at the Pentagon the day it was attacked, so I don't accept the concept of 'gee, I don't know what it's like.' "

Prince is currently visiting the detention center at Guantanamo Bay in Cuba to meet his client. He was denied a meeting with Mohammed on Wednesday due to procedural problems; he will try again today.

Before Prince headed to Guantanamo, he said he had no idea whether Mohammed will accept him as his lawyer. He says he's gone over what he's going to say "about a hundred times a day."

He's been reading the Quran and has met with psychologists and other lawyers who have represented accused terrorists. "This would not be the first time I've met with a client who initially did not want, if you will, court-appointed counsel," he said. "I've had clients call me almost any name in the book. I've had them refuse to come see me." Meet the attorney defending suspected 9/11 mastermind »

Still, Prince realizes that this is different. Very different.

Mohammed has been in custody since he was caught in Rawalpindi, Pakistan, in 2003. He was transferred from a secret location to Guantanamo in 2006. The government says he confessed to his involvement in the September 11 attacks and many other terrorist plots.

The government said in February that six terror suspects, including Mohammed, would go before military commissions and could face the death penalty if it is judged they were involved in the September 11 attacks. The proceedings are governed by the Military Commissions Act, which Congress passed to handle arrestees in the war on terror. See the terror suspects who could face the death penalty »

The act requires detainees have access to lawyers as well as to any evidence presented against them. They also will have the right to appeal a guilty verdict, potentially through a civilian appeals court and perhaps the U.S. Supreme Court, according to the act. Watch general describe charges against al Qaeda suspects »

In the case of Mohammed, the government acknowledged that he was subjected to waterboarding, a harsh interrogation technique that many experts believe violates the Geneva Conventions' ban on torture. Waterboarding involves strapping a person to a surface, covering the face with cloth and pouring water over the cloth to imitate the sensation of drowning.

Prince finds that extremely troubling because, he says, a civilian court would never admit evidence gained through a coerced statement. The government says Mohammed has confessed to September 11 and other terror plots.

"Even the greenest deputy sheriff or rookie police officer in Skunk Hollow County knows that if you rough up a defendant, anything he says after that is not going to be admitted into court," Prince said. "The officer might not like those rules, but he understands them and will abide by them."

But a judge in a military commission could have it entered into evidence. "We have created a system under the military commissions that says, in essence, 'if he was roughed up but what he says still seems reliable, we'll accept it any way.' And that's just wrong."

Prince says there are other complications. He may not have the chance to cross-examine Mohammed's accusers and may not see all the evidence to be put forward in court. Watch families of 9/11 victims push for fair trials »

Prince doesn't believe that Mohammed can get a fair trial and says the country risks trashing "our constitutional values when it becomes convenient to do so."

"I don't want to impugn anyone's character, but this is where Ronald Reagan's term 'trust but verify' will come into play," he said.

The military has assigned him a three-person team consisting of another lawyer, an intelligence analyst and a paralegal. The American Civil Liberties Union and the National Association of Criminal Defense Lawyers have also teamed up to find volunteers to help Prince and the other lawyers defending accused terrorists at Guantanamo Bay.

Norman Reimer, the executive director of the NACDL, explained the daunting task this way:"It's going to require all of the ingenuity and resources, not just to defend the accused but to defend the American system of justice and what we stand for in the world. That's what this is about."

Two lawyers from Boise, Idaho, have agreed to help Prince. No strangers to terrorism cases, David Nevin and Scott McKay won an acquittal for a Saudi man who faced terror charges.

Prince for years ran a small practice in Richmond, Virginia. But last year, the reservist was called to active duty and spent six months in Iraq. He never thought this would be his next assignment.

"I could have said, 'No,' " he said before adding, "I don't think I would have been doing honor to myself or honor to my calling." E-mail to a friend

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