The Senate approved the $631 billion National Defense Authorization Act for fiscal year 2013 with an amendment that intends to protect U.S. citizens and residents from indefinite detention without trial, but may actually extend the president’s disputed authority to do so to Congress.

The bill was approved on December 4 by a vote of 98-0 after days of debate and hundreds of amendments that included, among others, abortion insurance coverage to victims of rape in the military, stronger sanctions against Iran, and an amendment from Sen. Dianne Feinstein (D-Calif.) that intended to prohibit the detention of U.S. citizens and residents without trial, but could end up doing more harm than good, critics say.

Last year the annual National Defense Authorization Act (NDAA) for 2012 passed in a fury of controversy over provisions that gave the military unprecedented power to seize suspected terrorists anywhere in the world, including American citizens on U.S. soil, and keep them locked up indefinitely without charge or trial. The 2012 version of the annual military spending bill gave the president and future presidents the unfettered authority to wage war against Al Qaeda, the Taliban and “associated forces,” without defining what those might be. It made those designated as “enemy combatants” subject to indefinite detention, extraordinary rendition and military tribunals without requiring their knowledge or willful intention to provide “material’ or “substantial support.

Indigenous Peoples worried that the legislation could be used against them for asserting their rights to self-determination and sovereignty or for protecting their lands and resources against exploitation by governments or corporations.

On November 29, 2012, the Senate approved by a vote of 67-29 (20 Republicans and 46 Democrats) Feinstein’s amendment that critics of the measure say has loopholes so large that it might actually extend the president’s “constitutionally questionable” ability to authorize indefinite detention.

The language in the Feinstein amendment is as follows: "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."

Policymic cites two problems with the amendment’s language. The first is that it extends only to citizens or permanent legal residents, in violation of the due process requirement of the Fifth Amendment. The second is the language of the final part of the amendment: “unless an Act of Congress expressly authorizes such detention.”

The American Civil Liberties Union objected to both issues in a letter to lawmakers November 29. “The constitutional requirements of due process of law apply to all persons within the United States. The 5th Amendment to the Constitution states that “No person shall be…deprived of…liberty…without due process of law,” the letter said. “Moreover, we are very concerned that the Feinstein amendment implicitly authorizes domestic military detention. By seeking to protect only United States citizens and legal permanent residents, the amendment could be read to imply that indefinite military detention of any other persons apprehended within the United States was authorized in 2001 and was lawful,” the ACLU wrote, referring to the Authorization for Use of Military Force, the founding document of the “war on terror” that was passed the week after the 9/11 attacks. “In addition, 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 ACLU wrote.

The Feinstein Amendment also fails to define what “trial” means, leaving the controversy over the legitimacy or fairness of military commissions unresolved.

Obama had asked for a military spending appropriation of $614 billion, of which $89 billion would go to the war in Afghanistan, according to an Agence France Press report, but the Senate increased the total amount of the 2013 NDAA by $17 billion, even though legislators and the president are struggling to avoid hundreds of billions of dollars in automatic spending cuts that kick in next month if no deficit reduction deal is reached.

The NDAA 2013 bill now goes to the House of Representatives to be reconciled with a version passed earlier this year before it goes to the president for signature.