Audio Transcript:

MARCO WERMAN: I'm Marco Werman, and this is The World, a co-production of the BBC World Service, PRI, and WGBH Boston. President Obama addressed the graduating class at the US Naval Academy today. He promised the young officers that he would only send them into harm's way �when it is absolutely necessary.� Mr. Obama also echoed his remarks from Thursday, when he defended his plan to close the Guantanamo detention center.

PRESIDENT OBAMA: Yesterday, I visited the national archives and the halls that hold our Constitution, our Declaration of Independence, and our Bill of Rights. I went there because as our national debate on how to deal with the security challenges that we face proceeds, we must remember this enduring truth: the values and ideals in those documents are not simply words written into aging parchment. They are the bedrock of our liberty and our security.

WERMAN: President Obama has vowed to shut down the Guantanamo prison within a year. But there are a number of legal questions to be resolved first, as The World's Jason Margolis explains.

JASON MARGOLIS: The president said it plainly yesterday: he doesn't know what to do with some detainees in Guantanamo.

OBAMA: And I have to be honest here. This is the toughest single issue that we will face. We're going to exhaust every avenue that we have to prosecute those at Guantanamo who pose a danger to our country. But even when this process is complete, there may be a number of people who cannot be prosecuted for past crimes in some cases because evidence may be tainted.

MARGOLIS: The President suggested some of those detainees may be moved to maximum security prisons in the US. But overall, he's given no clear indication for how such cases may be handled. That's because there's no obvious solution, says Amos Guiora, Professor of Law at the University of Utah.

AMOS GUIORA: It's hard. It takes time. And I think what the President is doing is -- I think his speech in essence reflects, some kind of an inner tension within himself as to what's the way to most effectively, legally move forward which I think is legitimate. I think it's a legitimate process.

MARGOLIS: Guiora says the President is brainstorming his options publicly, engaging the American people in the debate. The first question the President faces: can combatants in Guantanamo be legally detained without trial indefinitely? John Hutson is Dean of the Franklin Pierce law school in Concord, New Hampshire.

JOHN HUTSON: �Indefinitely� is a difficult word and probably somewhat misleading. The Geneva conventions and years and centuries of history basically say that you can detain people on the soil of a particular country during the course of hostilities, and then at the cessation of the hostilities they should be released.

MARGOLIS: But there's no clear end to the war on terrorism. Just as there's no clear consensus on whether it's a war in the first place. President Obama says he prefers prosecution for detainees. But, Mr. Obama says, that's not always possible because evidence �may be tainted�. Hutson says even that raises questions.

HUTSON: Tainted evidence can mean one of a couple of things. One is that it's completely inadmissible. Is it completely inadmissible because it's unreliable? Or do we know that it's reliable but there's another problem? If it has been achieved through torture, then it's just unreliable. And detaining somebody on the basis of evidence that is unreliable -- in other words, there is no evidence because it was derived through torture, that creates problems.

MARGOLIS: One option the President could take to hold certain detainees without trial would be to ask Congress for approval. This is a problem for some human rights lawyers. Shayana Kadidal is a senior managing attorney for the Guantanamo Project at the Center for Constitutional Rights.

SHAYANA KADIDAL: If the President goes to Congress and gets authority to do so which is what he says he wants to do, you really are basically going to be re-creating Guantanamo on American soil under the cover legality, but it's not going to be anything different in substance. The only difference is that the Bush administration said they can do it and it didn't matter what the courts and Congress said. This would be Obama doing the same thing, except with approval from the Democratic Congress.

MARGOLIS: And then there's the question: would Congress approve whatever the President comes up with? For The World, I'm Jason Margolis.