On “Black Friday,” a record number of Americans purchased firearms. Just a few days later, the Senate enacted a measure that could eventually be used to imprison some of those citizens as terrorist suspects, or “unprivileged combatants.”

“Someone who has guns, someone who has ammunition that is weatherproofed, someone who has 7 days of food in their house” could be treated as a potential terrorist and be subject to indefinite military detention, warned freshman Senator Rand Paul (R-Kentucky) in a detailed and impassioned speech to the Senate opposing S.1867, the National Defense Authorization Act (NDAA). Section 1031 of that measure allows the indefinite military detention of any individual – including a U.S. citizen – who is designated a suspected terrorist or “unlawful combatant.” As Senator Paul pointed out, existing laws and official policy guidelines are replete with open-ended definitions under which law-abiding U.S. citizens could be regarded as actual or potential terrorists.

While insisting that the measure was chiefly intended to deal with the amorphous threat posed by al-Qaeda, Senator Lindsey Graham (R-South Carolina), one of the most enthusiastic supporters of the bill, admitted in a floor speech that Section 1031, “the statement of authority to detain, does apply to American citizens and it designates the world as the battlefield, including the homeland.”

In principle, this means nothing less than universal martial law, to the extent the U.S. military has the power to enforce it. On that assumption, U.S. citizens identified as “enemies” can be seized anywhere on the planet, including on American soil, and imprisoned under military jurisdiction either at home or abroad. Proposed amendments that would remove or modify that language were voted down by the “World’s Greatest Deliberative Body.”

As summarized by Christopher Anders, senior legislative counsel for the ACLU, this measure “puts military detention authority on steroids and makes it permanent,” thereby putting U.C. citizens “at greater risk of being locked away by the military without charge or trial.”

Playing to that element of his constituency that still cares about civil liberties, President Obama has threatened to veto the measure – not because it annihilates whatever is left of the Anglo-Saxon guarantees of individual liberty, but rather because it intrudes on what he regards as plenary presidential authority to imprison or execute people at whim. In fact, proposed language exempting U.S. citizens from military detention was removed from the bill at the behest of the White House, as civil liberties activist David Kopel points out.

The Obama administration acknowledges the existence of a secretive “kill list” of citizens subject to summary execution – whether by way of a hit team, or a drone-fired missile. In recent weeks, the administration has carried out two executive-ordered “hits” in Yemen against alleged terrorism advocate Anwar al-Awlaki and his 16-year-old son (who had gone to that country in a frantic effort to find his father).

A president claiming the authority to kill a citizen without even the most rudimentary form of due process certainly wouldn’t scruple to imprison citizens without trial or judicial review of any kind. The only dispute between the White House and the Senate involves the question of primacy – specifically, whether the president’s powers are supreme and illimitable, or whether they are subject to legislative restrictions of some kind. In either case, the NDAA would destroy whatever remains of habeas corpus, the foundational civil liberties guarantee in Anglo-Saxon legal tradition.

Habeas corpus (Latin for “present the body”) refers to the ancient requirement that an individual arrested for a crime must be immediately brought before an independent judge and either formally charged or set free. This is intended to prevent kings and other rulers from conducting arbitrary arrests and open-ended imprisonment, without trial, of people regarded as enemies of the State.

Article I, section 8 of the U.S. Constitution specifies that “the privilege of the Writ of Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it.” This loophole-laden provision isn’t an ironclad guarantee against tyranny. However, it is indisputably clear that the United States presently confronts neither an invasion nor a rebellion that would meet the constitutional standard for the temporary suspension of habeas corpus – let alone the permanent abolition of that guarantee in the name of a universal war against unspecified enemies that will continue in perpetuity.

Abhorrent as it is, the NDAA is not a revolutionary development; instead, it fortifies and institutionalizes existing policies. Five years ago Congress passed the Military Commission Act, under which the president was given permission to imprison anyone he chooses to designate as an “unlawful enemy combatant.” Although then-Senator Barack Obama opposed the 2006 Military Commissions Act, he signed into law a virtually identical measure when it was folded into the 2010 Defense Authorization Bill.

The NDAA itself is the immediate outgrowth of the “Enemy Belligerent, Interrogation, Detention, and Prosecution Act of 2010,” a measure proposed by Senators John McCain (R-Arizona) and Joe Lieberman (I-Connecticut). One section of that bill dealing with “Detention without Trial of Unprivileged Enemy Belligerents” stated that suspects “may be detained without criminal charges and without trial for the duration of hostilities against the United States or its coalition partners.”

That provision, in slightly modified form, was incorporated into the NDAA. Those subject to military detention, according to the NDAA, include anyone “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.”  The carefully ambiguous language translates into a license to imprison practically anybody who is accused of providing unspecified “support” for any group the U.S. government doesn’t like.

Some Americans still cherish the notion that we are freer than people in such countries as Cuba, Iran, Syria, or Saudi Arabia. The brutal truth is that Americans — like Cubans, Iranians,  Syrians, and subjects of the House of Saud – exercise whatever freedoms will still enjoy only by grace of our master in the White House and his duly appointed agents. They may leave us alone entirely; they may disturb us with relatively slight impositions; they may suddenly descend on us in fury to deprive us of our homes, our families, and our lives. According to what our rulers are pleased to call the “law,” the choice is entirely theirs.

John Locke, who greatly influenced America’s Founders, pointed out that “slavery” consists of being “subject to the incessant, uncertain, arbitrary will of another man” and that “absolute arbitrary power” is the practice of “governing without settled standing laws.” The NDAA, like similar measures that preceded it, is designed to enslave Americans by leaving us at the mercy of those wielding arbitrary power.

“A nation of slaves is always prepared to applaud the clemency of their master, who, in the abuse of absolute power, does not proceed to the last extremes of injustice and oppression,” wrote British historian Edward Gibbon. At this point, the ability of our rulers to kill and imprison us is restrained only by the limits of their depraved imagination.