Even American citizens arrested in the United States could face perpetual detention in military prisons without charge or trial under draconian new presidential powers unless Barack Obama vetoes a massive Pentagon spending bill.
The sweeping new "antiterrorist" measures could also ensnare Canadians or other foreigners picked up in the United States or overseas.
"The homeland is part of the battlefield and people can be held without trial whether an American citizen or not," said Senator Lindsey Graham, a South Carolina Republican, one of the key backers of the new authority.
For instance, U.S. agents tipped off by their Canadian counterparts as part of new intelligence-sharing pacts could detain a Canadian, ship him to Guantanamo and imprison him there forever.
If Mr. Obama signs the legislation, it will make the United States "an outlier in the international community," legalizing indefinite detention without charge in military prisons for citizens and foreigners alike, said Andrea Prasow, senior counterterrorism counsel at Human Rights Watch.
Slipping controversial clauses into important omnibus legislation is an old congressional manoeuvre designed to raise the consequences of a presidential veto.
Not only are rights campaigners outraged. Some senior military commanders have also stepped up to publicly denounce the latest "militarization" of America's justice system.
"We know that politicians of both parties love this country and want to keep it safe. But right now some in Congress are all too willing to undermine our ideals in the name of fighting terrorism," retired generals Charles Krulak, a former Marines Corps commandant, and Joseph Hoar, a former Central Command chief, said in an open letter opposing the powers.
Mr. Obama vaguely threatened to veto earlier versions of the bill, but if the President makes good on his threat and refuses to sign the National Defence Authorization Act – the new powers are tucked inside – he risks a political firestorm with his opponents accusing him of depriving America's military of funds.
Mr. Obama's track record on sweeping presidential powers in the war against terrorism is mixed. He promised to shutter Guantanamo but kept it open. The President also set an extraordinary precedent when he ordered the assassination of al-Qaeda cleric Anwar al-Awlaki, an American-born citizen, using a missile-firing Predator drone.
At least one senior Democrat, Senator Carl Levin, a co-sponsor of the bill, says the White House sought the new powers of indefinite military imprisonment.
The latest version of the bill, agreed to by both the Democrat-controlled Senate and the Republican-controlled House of Representatives, effectively makes the entire planet a "battlefield" where military apprehension, detention and trial of the "enemy" is expressly allowed.
Constitutional experts, including some from the far right, argue those powers flout the most basic of rights, habeas corpus, not to be detained without just cause.
"The bill is an historic threat to American citizens and others because it expands and makes permanent the authority of the president to order the military to imprison without charge or trial," said Christopher Anders of the American Civil Liberties Union in a conference call Tuesday. "No corner of the world would be off limits."
Canadians have already suffered the long reach of enhanced U.S. counterterrorism powers, abetted sometimes by Canadian agents. For instance, Maher Arar was intercepted changing planes in New York, shipped to Syria and tortured. Under the new provisions, he could have been imprisoned in Guantanamo indefinitely. Similarly, secret Canadian CSIS documents show that the CIA wanted another Canadian, Abousfian Abdelrazik, sent to Guantanamo Bay, the U.S. offshore prison on a leased naval base in Cuba.
Under the new powers, even American citizens picked up inside the United States on suspicion of aiding al-Qaeda or other violent, extremist Islamic groups could be sent to Guantanamo.
If Mr. Obama signs the National Defence Authorization Act giving him the new powers, the controversy will almost certainly wind up in the Supreme Court.