The Washington-based Council on American-Islamic Relations (CAIR) said the legislation, which was signed into law by President Barack Obama on Saturday, will forever be seen as a "stain on our nation's history" because it authorizes the military to arrest and indefinitely detain American citizens suspected of terrorism without charge or trial.
As the legislation passed through Congress, CAIR said in a press release that it issued a number of statements and alerts urging a presidential veto if the detention provisions were not removed.
In a statement reacting to the signing of the legislation, CAIR said, "It is deeply troubling that (the bill) became law with the detention provisions intact. We believe it is unconstitutional for our military to become a police force that would hold American citizens indefinitely without the right to trial or even to hear the charges brought against them.
"Permitting indefinite detention of American citizens without trial shatters a cornerstone of our democracy -- the right of the individual to due process. Every elected official who participated in the formation and passage of this law has violated their oath to support and defend the Constitution.
"While it is encouraging to hear that the current administration will interpret the detention provisions 'in a manner that ensures that any detention it authorizes complies with the Constitution, the laws of war, and all other applicable law,' we have no assurances that future administrations will act in a similar manner.
"This ill-conceived and un-American legislation will forever be seen as a stain on our nation's history -- one that will ultimately be viewed with embarrassment and shame."
In signing the legislation, President Obama said: "I want to clarify that my administration will not authorize the indefinite military detention without trial of American citizens. Indeed, I believe that doing so would break with our most important traditions and values as a nation."