Author and political consultant Naomi Wolf, also a vocal critic of the NDAA, speaks to reporters during a news conference outside the Federal Court in Manhattan March 29, 2012. REUTERS

A federal judge has ruled that provisions of a new law authorizing the U.S. government to indefinitely detain citizens violate the First and Fifth amendments, undercutting the Obama administration's claim that the measures are constitutional.

Debate over the National Defense Authorization Act of 2011 has centered around language that permits the American government to indefinitely detain people it suspects of being terrorists, even if they are U.S. citizens captured on American soil. The measure prompted an animated argument in the Senate, with some Democrats warning of an unprecedented risk of eroding civil liberties.

Proponents of the bill argued that the authority to indefinitely detain people who fit the criteria of being designated terrorists already exists -- a view shared by the Obama administration -- and Senate critics who ultimately voted for the bill agreed to disagree on whether the legislation grants the executive branch new powers.

A group of activists and intellectuals that includes Daniel Ellsberg, Christopher Hedges, Noam Chomsky, Jennifer Bolen and Birgitta Jonsdottir, a member of parliament in Iceland, sued the administration, contending that the bill violated their free speech rights under the First Amendment and the Fifth Amendment's guarantee of due process.

Southern District of New York judge Katherine Forrest vindicated their argument on Wednesday, maintaining that the plaintiffs had a legitimate fear of being targeted for their roles as outspoken critics of government policy and their associations with subversive groups or people.

This court is acutely aware that preliminarily enjoining an act of Congress must be done with great caution, she wrote. However, it is the responsibility of our judicial system to protect the public from acts of Congress which infringe upon constitutional rights.

For example, Forrest noted that Hedges, a journalist, has written about and interviewed members of numerous terrorist organizations, including Al Qaeda and Hamas, and that some of his articles appear on Islamic or jihadist websites. Alexa O'Brien, a journalist and organizer for the New York-based activist group Day of Rage, testified about withholding articles covering Al Qaeda and the Taliban for fear of government reprisal. The activist Kai Wargalla, whose organization does work relating to the antisecrecy organization Wikileaks, said she had curtailed some of her groups' planned actions for the same reason.

Those plaintiffs have already experienced a chilling of specific associational and expressive conduct, Judge Forrest wrote, adding that wach plaintiff acted as a result of his/her understanding (or lack thereof) of the scope of the indefinite detention provisions in the NDAA.

The human costs associated with altering their behavior--both in their personal, day-to-day lives as well as their professional lives--are certainly cognizable costs undertaken based upon their reasonable fear, Forrest wrote.

Forrest also rejected the Obama administration's argument that the NDAA does not confer any new powers. The administration has said that the indefinite detention mechanism was already provided for under an Authorization for the Use of Military Force that Congress passed shortly after Sept. 11, 2001. That authorization, which allows the government to deploy all necessary and appropriate force against the perpetrators of the 9/11 attacks or anyone who aided them, has served as the legal justification for counterterror initiatives ranging from holding detainees without trial at Guantanamo Bay to launching drone strikes in Yemen and Somalia.

But arguing that the NDAA only reaffirms existing authority would be contrary to basic principles of legislative interpretation that require Congressional enactments to be given independent meaning, Forrest wrote.

To find that [the indefinite detention provision] is merely an affirmation of the AUMF would require this Court to find that [the indefinite detention provision] is a mere redundancy--that is, that it has no independent meaning and adds absolutely nothing to the Government's enforcement powers, Forrest wrote.

Democrats and civil liberties advocates have been vocal in their criticism of the NDAA, warning that it enshrines and expands the president's power to discard safeguards essential to the justice system.

It has also attracted the rare spectacle of bipartisan dissent - although Senate Democrats set their concerns aside in approving the bill, some Republican and Democratic lawmakers have since sharply objected to the indefinite detention provisions, and demonstrations against the bill have featured members of both Occupy Wall Street and of the Tea Party.

The White House threatened to veto a new House version of the National Defense Authorization Act on Wednesday, objecting in part to a measure that would tighten the requirements for transferring detainees. The administration said in a statement that the provision would threaten to compromise the executive's ability to act swiftly and flexibly, but made no mention of separate amendments aimed at reining in indefinite detention.

President Obama issued waivers in February that shielded most potential detainees from military detention, making it unlikely that the civilian justice system will cede many cases to the military.