WASHINGTON — President Obama set aside his veto threat and late Wednesday signed a defense bill that imposes restrictions on transferring detainees out of military prisons in Afghanistan and Guantánamo Bay, Cuba. But he attached a signing statement claiming that he has the constitutional power to override the limits in the law.
The move awakened a dormant issue from Mr. Obama’s first term: his broken promise to close the Guantánamo prison. Lawmakers intervened by imposing statutory restrictions on transfers of prisoners to other countries or into the United States, either for continued detention or for prosecution.
Now, as Mr. Obama prepares to begin his second term, Congress has tried to further restrict his ability to wind down the detention of terrorists worldwide, adding new limits in the National Defense Authorization Act of 2013, which lawmakers approved in late December.
The bill extended and strengthened limits on transfers out of Guantánamo to troubled nations like Yemen, the home country of the bulk of the remaining low-level detainees who have been cleared for repatriation. It also, for the first time, limited the Pentagon’s ability to transfer the roughly 50 non-Afghan citizens being held at the Parwan prison at B... at a time when the future of American detention operations there is murky.
Despite his objections, Mr. Obama signed the bill, saying its other provisions on military programs were too important to jeopardize. Early Thursday, shortly after midnight, the White House released the signing statement in which the president challenged several of its provisions.
For example, in addressing the new limits on the transfers from Parwan, Mr. Obama wrote that the provision “could interfere with my ability as commander in chief to make time-sensitive determinations about the appropriate disposition of detainees in an active area of hostilities.”
He added that if he decided that the statute was operating “in a manner that violates constitutional separation of powers principles, my administration will implement it to avoid the constitutional conflict” — legalistic language that means interpreting the statute as containing an unwritten exception a president may invoke at his discretion.
Saying that he continued to believe that closing the Guantánamo prison was in the country’s fiscal and national security interests, Mr. Obama made a similar challenge to three sections that limit his ability to transfer detainees from Guantánamo, either into the United States for prosecution before a civilian court or for continued detention at another prison, or to the custody of another nation.
It was not clear, however, whether Mr. Obama intended to follow through, or whether he was just saber-rattling as a matter of principle. He made a similar challenge a year ago to the Guantánamo transfer restrictions in the 2012 version of the National Defense Authorization Act, but — against the backdrop of the presidential election campaign — he did not invoke the authority he claimed.
Several officials said that it was not certain, even from inside the government, what Mr. Obama’s intentions were. While the signing statement fell short of a veto, they said its language appeared intended to preserve some flexibility for the president to make a decision later about whether to make a new push to close the Guantánamo prison amid competing policy priorities.