Congress recently passed its 2014 defense authorization bill. In doing so, for the first time the legislative body voted to make it easier for President Obama to achieve his longtime goal of closing the prison at Guantánamo Bay. The bill lifts the restrictions on transferring prisoners to foreign countries, meaning that the administration can now begin to move the half of the current detainees (seventy-nine out of 158) who have already been cleared for transfer out of the prison. The legislation, however, does maintain the current restrictions on transferring Guantánamo detainees into the United States for trial or imprisonment.

How did this happen? In a lengthy Daily Beast piece in the week prior to the vote, Daniel Klaidman outlined how the politics of the issue had changed significantly over the past year, pointing to three broad factors. First, he writes, the political climate “had been steadily shifting away from concerns about national security” as the United States has wound down the wars of the past decade. Second, the Obama administration began to devote considerably more time and energy to the effort to close the prison, highlighting it in high-profile speeches in the spring and appointing special envoys at both the State and Defense Departments who would be tasked with advancing it.

Third, Klaidman notes that one particular argument began to have some sway over skeptics in Congress—namely, the cost of the prison. Adam Smith, a House Democrat, reviewed budget information from the Defense Department and discovered that at Guantánamo, the government was spending $2.7 million per detainee, per year, as opposed to the only $78,000 per year it would cost to keep prisoners at Supermax prisons within the United States. Smith told Klaidman that in an era of declining budgets, this line of argument “was the one thing that changed the debate.”

In some ways, this is part of a larger trend that we’ve seen in national-security debates over the past year. In July, following Edward Snowden’s revelations about the NSA, an effort in the House of Representatives led by Representatives Justin Amash and John Conyers to outlaw the NSA’s bulk collection of metadata failed by only twelve votes. And in September, after President Obama announced that he would go to Congress to seek its approval for conducting military strikes against Syria, the opposition to this proposal in Congress and the public was unexpectedly widespread and intense. This contributed to the president’s decision to forgo the attack and instead pursue a diplomatic option to attempt to rid Syria of its chemical weapons. The recent Guantánamo vote fits this pattern in that it is another example where arguments that a given policy course is necessary for reasons of national security (whether detaining prisoners, collecting data or attacking another country) are now treated with a higher degree of skepticism than in the past. The straitened budget conditions naturally contribute to this mentality as well, even if the cost of any one of these policies is comparatively small in the scope of the overall defense or federal budget.

The reaction to the vote in Congress may also serve as an indicator of this trend. Predictably, civil-liberties groups have celebrated the result. Its opponents, meanwhile, have been relatively silent. This is a pretty significant shift from even just earlier this year. After President Obama announced in the spring that he was going to renew his effort to shutter the facility, leading congressional Republicans of both chambers swore their opposition to this goal. Now, a major step toward that end is being taken, and from a political point of view it appears to be mostly a nonissue.

If supporters of the effort to close Guantánamo do eventually succeed, it will be in part because this trend has continued, and this will probably be the model for how it happens. Congress will continually have to revisit the remaining restrictions on transferring detainees to U.S. soil. As time goes on—assuming that this pattern holds and barring an event like another major terrorist attack—the argument that bringing the remaining Guantánamo prisoners into the United States represents an unacceptable security threat may lose its currency. And more budget-conscious congressmen may continue to be persuaded by the fiscal argument mentioned above, seeing the facility as an unnecessary expense for a marginal or nonexistent security gain.

It is worth noting that the end of Guantánamo would not necessarily mean the end of indefinite detention—perhaps the defining and most controversial aspect of the prison. Indeed, under the administration’s own stated plans, forty-six of the prisoners there currently are deemed too dangerous to release, but also cannot be prosecuted due to a lack of admissible evidence. If all the restrictions were lifted, they would presumably be transferred into facilities within the United States, but still held indefinitely.

Nevertheless, this is a meaningful step by any standard. As Benjamin Wittes wrote at Lawfare, even those who support indefinite detention or keeping Guantánamo open shouldn’t want to see the U.S. government “holding people we don’t need or want to be holding.” In Wittes’s words, the vote in Congress represents “a big win for the Obama administration—and for common sense.” Yes, it does.

Image: Flickr/Medill DC. CC BY 2.0.