The White House will not add another detainee to the prison camps at Guantánamo, the Pentagon’s top lawyer said Tuesday, acknowledging that congressional restrictions have brought captive releases to a standstill for a year.

Defense Department General Counsel Jeh Johnson made the stark disclosures at the conservative Heritage Foundation in Washington D.C., at a time when the Obama administration is resisting legislation meant to strengthen the military role in terror detentions and prosecutions.

Congress wants to grow the prison camps in southeast Cuba that the White House wants to close.

As of Tuesday, they held 171 captives, including dozens cleared for release if the State Department can secure safe resettlement agreements and Secretary of Defense Leon Panetta signs a waiver that Johnson declared “onerous and near impossible to satisfy.”

He added: “Not one Guantánamo detainee has been certified for transfer since this legal restriction has been imposed.”

That was a year ago. Since then, only two captives have left the camps — both dead, one of a suspected suicide and the other of a suspected heart attack.

The focus of Johnson’s remarks was on how to prosecute terror cases. He ticked off a series of administration successes in the federal courts, including the recent guilty plea by the so-called “underwear bomber,” and he reported that the White House had prevailed in the last 10 habeas corpus challenges by Guantánamo captives in the federal courts.

“Lawyers in the Department of Justice and the Department of Defense have worked hard to build credibility with the courts,” he said, “by conducting a thorough scrub of the evidence and the intelligence before we put forward our case for detention in the courts.”

But the first question he received was not on detention strategy but on the White House authority in using drones to kill Anwar al-Awlaki of the Al-Qaida in the Arabian Peninsula, a prominent Yemeni-American militant on Sept. 30 in Yemen.

“I am satisfied that the military is conducting itself in full compliance with domestic legal authorities, laws of armed conflict and international law,” he said.

Johnson also left no room for ambiguity on whether there were conditions under which the Obama White House might use Guantánamo for future detention or prosecution of terror suspects beyond those were currently there — four already convicted of war crimes and six in the chute for death-penalty prosecutions.

“It is the firm policy of this administration not to add to the Guantánamo population,” he said, in response to a question. “The president pledged to close Guantánamo and we are committed to that goal.”

No new captive has been added to the prison camps since March 2008 when the Bush administration brought in Muhammed Rahim al Afghani. He was described as a high-level al Qaeda captive who had been previously held by not the military but the CIA at since closed black sites.

Congress is considering requiring military custody of many terror suspects, including possibly foreigners arrested on U.S. soil. In an unusual alliance, a former Bush administration Defense Department senior detention official, Charles ‘Cully’ Stimson, hosted the Heritage event to give Johnson a platform to argue against the restrictions.

“We must use every tool at our disposal,” Johnson argued. “There is danger in over-militarizing our approach to al-Qaida and its affiliates.”

That’s because, he said, the enemy is “an unconventional non-state actor that does not play by the rules, operates in secret, observes no geographic limits, constantly morphs and metastasizes, and continues to look for opportunities to export terrorism to our homeland.”

One possible tool is war court prosecutions at U.S. military bases, depending on the latest legislation. But Johnson would not confirm reports from Charleston, S.C., that Defense Department teams had recently inspected the Navy brig there as a possible site for future military prisoners. The Bush administration held former enemy combatants José Padilla and Ali al Marri there before deciding to prosecute them in federal courts and winning convictions

“We have from time to time looked at alternate locations” in the past 2.5 years, he said. “That’s probably about all I want to say.”