WASHINGTON -- The Senate took a step Thursday toward ending the indefinite detention of Americans in the U.S., voting for a narrow amendment that some civil liberties groups opposed, even though they said it was in the right direction.

The measure, offered by Sen. Dianne Feinstein (D-Calif.) as an amendment to the National Defense Authorization Act of 2013, specifies that citizens and legal residents suspected of terrorism in the U.S. cannot be held without trial indefinitely.

"I know this is a sensitive subject, but I really believe we stand on the values of our country, and the value of our country is justice for all," said Feinstein before the Senate voted 67 to 29 to add her provision to the NDAA.

Civil libertarians had problems with her amendment, even though many regarded it as a positive step.

The key sentence in her measure says: "An authorization to use military force, a declaration of war, or any similar authority shall not authorize the detention without charge or trial of a citizen or lawful permanent resident of the United States apprehended in the United States, unless an Act of Congress expressly authorizes such detention."

First, the rights groups argued, the measure does not provide justice for all, because it does not apply to non-citizens or Americans caught overseas.

"The constitutional requirements of due process of law apply to all persons within the United States," a coalition of 20 groups wrote in a letter to Feinstein Thursday. "The 5th Amendment to the Constitution states that 'No person shall be…deprived of…liberty…without due process of law.'"

The groups also said they worried that part of that sentence suggests that Congress believes it can write laws that abridge basic constitutional protections in the future.

"The clause 'unless an Act of Congress expressly authorizes such detention' could be read to imply that there are no constitutional obstacles to Congress enacting a statute that would authorize the domestic military detention of any person in the United States," the letter said.

Senators who had supported the detention of Americans in the past seemed to agree with the civil liberties groups.

One, Armed Services Committee Chairman Carl Levin (D-Mich.), pointed to the same exception. "This is a big 'unless,'" he said.

"I believe that the 2001 authorization for the use of military force authorized the detention of U.S. citizens when appropriate in accordance with the laws of war," said Levin, referring the authorization Congress passed after the 9/11 attacks.

Sen. Rand Paul (R-Ky.) an opponent of indefinite detention, said he believed the amendment does shield citizens, and said American terrorist suspects would be treated just like criminals and get trials, arguing that if Americans give up a basic constitutional right to trial, terrorists have won.

"People say, 'But these terrorists are horrible people.' Yes, they're horrible people, but every day and every night in our country horrible people are accused of crimes and they are taken to court," said Paul. "They have an attorney on our their side. They have a trial. People who we despise, people who murder and rape, are given trials by juries. We can try and we can prosecute terrorists."

President Barack Obama has pledged to never detain people caught in the United States -- perhaps making it an academic point during his presidency -- but if someone were to be grabbed and detained in the U.S., the extreme divergence of opinion among the lawmakers as to what the law does likely assures a court will eventually make a final determination.

Republican Sen. Lindsey Graham (S.C.), a supporter of detention, suggested matters were actually quite simple, and a judge would see it his way.

"When you're fighting a war, the goal is not to prosecute people, the goal is to win," Graham said. "How do you win a war? You kill them, you capture them and you interrogate them to find out what they're up to next."

The defense bill passed by the House contains no similar language. It was unclear if Congress would be able to mesh the two measures before the session of Congress ends. It was also unclear that the House would accept the change.

Michael McAuliff covers Congress and politics for The Huffington Post. Talk to him on Facebook.

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  • Interview A Member Of The Taliban

    <strong>Scenario:</strong> As a foreign correspondent on assignment in Afghanistan, you successfully contact Taliban representatives who take you to meet a mullah. After you've completed your interview and fact-finding mission, U.S. officials arrest you under suspicion of terrorism. <strong>How:</strong> Section 1021 (2) of the National Defense Authorization Act <a href="http://www.gpo.gov/fdsys/pkg/BILLS-112hr1540enr/pdf/BILLS-112hr1540enr.pdf" target="_hplink">grants power</a> to indefinitely detain "a person who was a part of or substantially supported al-Qaeda, the Taliban, or associated forces that are engaged in hostilities against the United States or its coalition partners." You're not sure if what you did was "substantial" or really "supported" anyone. It's quite possible that nobody does, as the text of the law doesn't define these words. This could take a while to sort out. In the recent hearing on a lawsuit challenging that section of the act, Judge Katherine Forrest asked an Obama lawyer if plaintiff Chris Hedges could be assured that he would not be subjected to detention under Section 1021, journalist Naomi Wolf <a href="http://naomiwolf.org/2012/03/ndaa-hearing-notes/" target="_hplink">noted</a>. Hedges is a Pulitzer prize-winning reporter who has worked extensively in Afghanistan and the Middle East. The administration attorney suggested that the specifics of Hedge's situation would make his detention unlikely, but responded, "I cannot say that today." While the Obama administration has said you're entitled to a trial as a U.S. citizen, this won't preclude you from a protracted journey through an encumbered court system charged with figuring out -- based on secret evidence -- why you were picked up. And if it this happens during a future administration, officials might not agree with Obama on your right to a trial.

  • Attend A Fundraiser

    <strong>Scenario:</strong> A local civil liberties group holds a swanky fundraising event and you, a wealthy philanthropist, write a sizable check. Sometime later, the group is placed on a watch list, which results in authorities arriving at your door, hauling you away. <strong>How:</strong> It's possible a portion of your money somehow got funneled to al-Qaeda or a pro-Taliban group or that somehow you became an indirect material supporter of what the National Defense Authorization Act calls an "associated force." But just what are "associated forces"? That question appeared to stump Obama administration lawyers when pressed by Judge Katherine Forrest during a recent hearing. "I don't have specifics," an attorney told her. Answering a later question about whether WikiLeaks could be construed as an "associated force," an administration lawyer suggested that it couldn't, unless there were a connection to the Taliban or al-Qaeda. If someone happens to be wrong about your case, you might sit in detention until the courts figure it out. Or, according to the act, you'll be released when officials determine it is "the end of the hostilities authorized by the Authorization for Use of Military Force."

  • Write A Book

    This hypothetical situation comes straight from this spring's hearing on a lawsuit challenging parts of the National Defense Authorization Act, as captured by <a href="http://naomiwolf.org/2012/03/ndaa-hearing-notes/" target="_hplink">Naomi Wolf</a>: <blockquote>Bruce Afran, lawyer for the plaintiffs, presented the hypothetical of a book that did not say how to make a bomb but simply expressed support for the political goals of the Taliban, or that made the case that the Taliban's view that the US government overreaches in occupying other countries, has merit. He and Judge Forrest discussed the hypothetical that such a book could be a bestseller and be on a book tour, generating comment throughout the Middle East. Judge Forrest simplified the example to a hypothetical of a book with only one sentence, and whose only sentence read: "I support the political goals of the Taliban'. She asked the government lawyers if such a book could be read as providing 'material support' for 'associated forces" under the NDAA. They did not rule it out. Judge Forrest pushed: "You are unable to say that [such a book] consisting of political speech could not be captured under [NDAA's Section] 1021?" Obama lawyers: "We can't say that."</blockquote>

  • Organize A Demonstration

    <strong>Scenario:</strong> Some societal injustice is prompting you to start a movement in protest. Hours after a particularly well-attended and rambunctious rally, you're approached by men in black suits who flash their badges and toss you in the back of their unmarked SUV. <strong>How:</strong> It's possible that you or one of your loosely connected crew of associates did something to make you a suspect linked to an "associated force." Or perhaps, according to another part of National Defense Authorization Act's Section 1021 (2), your actions constituted "substantial support" to a "person who has committed a belligerent act or has directly supported such hostilities in aid of [al-Qaeda or the Taliban]." Journalist and "Day of Rage" organizer Alexa O'Brien joined a recent lawsuit challenging sections of the act out of concern that she was being targeted as a potential terrorist threat. But at a hearing on the suit this spring, Obama administration officials did not alleviate such concerns, as <a href="http://naomiwolf.org/2012/03/ndaa-hearing-notes/" target="_hplink">Naomi Wolf has documented</a>: <blockquote>O'Brien produced into evidence a [Department of Homeland Security] memo that sought to link US Day of Rage to their cyberterrorism initiative. The government lawyer was given a chance by Judge Forrest to dispute the memo as fraudulent and did not do so.</blockquote>

  • Help Out A Friend

    <strong>Scenario:</strong> A good friend whom you've lost touch with contacts you, asking for help funding his around-the-world trip. You wire money and wait for him to return. Sometime later, there's a knock on your door. The people on the other side of it have questions about a sum of money you sent abroad to someone questionable. They ask you to come with them. <strong>How:</strong> You're finding it impossible to believe that your childhood friend became a terrorist or connected with al-Qaeda, the Taliban or "associated forces." But even if he did manage to get mixed up in some sketchy business, shouldn't there be an exception for you, his well-intentioned friend who was just helping someone in need? Not necessarily. At a recent hearing, Judge Katherine Forrest tried to get the Obama administration to <a href="http://naomiwolf.org/2012/03/ndaa-hearing-notes/" target="_hplink">give an assurance that "unwitting" support</a> could be protected, noting that there was no direct reference to such language in the law. Obama's attorney was unable to provide such a safeguard, instead arguing that the new law possessed the same exemptions contained within the Authorization for Use of Military Force Against Terrorists, which was passed by Congress after 9/11. The brief and broadly interpreted <a href="http://www.gpo.gov/fdsys/pkg/PLAW-107publ40/html/PLAW-107publ40.htm" target="_hplink">authorization</a> makes no mention of the word "unwitting," though.

  • Accidentally Provide Missiles To Insurgents

    <strong>Scenario:</strong> You're a flippant, billionaire playboy or -girl with a cool haircut and two Ph.D.s., one in nuclear fusion and the other in kicking ass. You get bored, so you decide to fight crime in Afghanistan and make a quick jaunt to Kandahar. In the process of taking on an encampment of Taliban insurgents, the firing mechanism for one of your missiles malfunctions, launching it thousands of feet into the air. It returns to Earth undetonated, only to be picked up by an enemy who uses it as the centerpiece of an improvised explosive device. When a U.S. mine-sweeping crew deactivates the makeshift bomb and finds your name emblazoned on the device, you're picked up. <strong>How:</strong> This appears to be a clear-cut case of "substantial support" to the Taliban or at least "associated forces" who wanted to do harm to U.S. troops. So much for your intentions of wanting to help out with a little vigilante justice. Any resulting court case could take ages.

  • Plan A Terrorist Attack

    <strong>Scenario:</strong> You're a total jerk and not a very big fan of America, so you decide that the best course of action is to take out your anger with an act of destruction on a densely populated city. You do some planning and set up your device, but when it comes time to use it, it malfunctions, leaving you injured and going to jail on a stretcher. <strong>How:</strong> You're an American citizen, you'll get your constitutional guarantee of a trial, right? If President Barack Obama's promises are followed, yes. But that doesn't mean you can't undergo some form of indefinite detention while you await trial. During a hearing on the lawsuit challenging parts of the new National Defense Authorization Act, Obama's lawyers were unable to say for sure if the trial promised in his signing statement would be a civilian or military one. This could have a heavy bearing on the nature of your detention. And if you were to commit such actions under the administration of another president, there's no telling how a new commander in chief would interpret the act, making your fate even less certain.