Is the National Defense Authorization (NDAA) Unconstitutional?

The National Defense Authorization Act (NDAA) is a United States federal law specifying the budget and expenditures of the U.S. Department of Defense.
Congress passes a version of this Act every year. H.R. 1540, the NDAA for fiscal year 2012, was passed in December and signed into law by President Obama on New Year’s Eve.
So why is the 2012 version of the NDAA getting so much attention? A controversial section in the law now gives the President authority to detain a person indefinitely without trial, a provision that critics assert to be unconstitutional.
Here is the language in the law:
Under Subtitle D—Counterterrorism, Section 1021 (a), it states, “In General – Congress affirms that the authority of the President to use all necessary and appropriate force pursuant to the Authorization for Use of Military Force includes the authority for the Armed Forces of the United States to detain covered persons (as defined in subsection (b)) pending disposition under the law of war.
(b) Covered Persons – A covered person under this section is any person as follows:
(1) A person who planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored those responsible for those attacks.
(2) 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, including any person who has committed a belligerent act or has directly supported such hostilities in aid of such enemy forces.”
President Obama released a “signing statement” in conjunction with his signature to the law which states in part, “my administration will not authorize the indefinite military detention without trial of American Citizens.”
The definition of  “covered persons” does not specifically exclude American citizens, however, creating debate as to its meaning.
Legal scholar Jonathan Turley states, “Indefinite detention of citizens is something that the Framers were intimately familiar with and expressly sought to bar in the Bill of Rights.”
Senator Lindsay Graham made a statement from the Senate floor in which he said, “the statement of authority to detain does apply to American citizens and it designates the world as the battlefield, including the homeland.”
Charles Stimson, a Senior Legal Fellow with the Center for Legal and Judicial Studies at The Heritage Foundation, argues that section 1021 does not create or expand federal authority to detain U.S. citizens indefinitely and without due process. He states, “The law regarding how U.S. citizens are handled, including the right to habeas corpus, is the same today as it was the day before it was passed.” He cites Section 1021(e) of the NDAA which states that “Nothing in this section shall be construed to affect existing law or authorities relating to the detention of United States citizens, lawful resident aliens of the United States, or any other persons who are captured or arrested in the United States.”
Several activists including journalists and civil libertarians have sued President Obama, Attorney General Eric Holder, Defense Secretary Leon Panetta and other members of the government demanding that Subsection 1021(b)(2) be removed or revised to more precisely define the meaning of “persons covered.”
On April 18 H.R. 4388 was filed by Congressman Scott Rigell (R-VA) which states,”…that nothing in the Authorization for Use of Military Force or the National Defense Authorization Act for Fiscal Year 2012 shall be construed to deny the availability of the writ of habeas corpus for any person who is detained in the United States.” The bill was cosponsored by 26 congressmen, including Quico Canseco (TX-23), Mike Conaway (TX-11), John Culberson (TX07), Mac Thornberry (TX-13), and has been referred to the Committee on Foreign Affairs and the Committee on Armed Services.