In a speech he gave a couple of months ago, President Obama said he was determined to guarantee "meaningful due process rights" for terrorism suspects. But it turns out he is committed to due process only when it achieves the result he wants.

Last week, the Defense Department's top lawyer declared that the president has the authority to detain people accused of belonging to or assisting terrorist groups even after they're acquitted. The only point of prosecuting them, it seems, is to create an impression of due process while continuing Bush detention policies that Obama has repeatedly condemned.

We already knew that Obama plans to keep 90 or so of the 229 men who remain at the Guantanamo Bay prison, which he has promised to close by January, in "prolonged detention" without trial. In his May speech the president said these prisoners "cannot be prosecuted" because there is not enough admissible evidence against them yet cannot be released because they "pose a clear danger to the American people."

But Obama promised to minimize the number of detainees who fall into that category. "Whenever feasible," he said, "we will try those who have violated American criminal laws in federal courts." If that's not possible, he said, suspected terrorists can be tried by military commissions, which "allow for the protection of sensitive sources and methods of intelligence gathering" and "for the presentation of evidence gathered from the battlefield that cannot always be effectively presented in federal courts."

Obama, who criticized the Bush administration for failing to give detainees due process, bragged about strengthening protections for the accused. Thanks to his reforms, he said, defendants tried by military commissions will have "greater latitude in selecting their own counsel" and "more protections if they refuse to testify"; introducing hearsay evidence will be harder, and statements elicited through "cruel, inhuman or degrading interrogation methods" will be banned.

But how "meaningful" can such due process rights be when a conviction is the only outcome the government plans to respect? "If you have the authority under the laws of war to detain someone," Pentagon General Counsel Jeh Johnson told the Senate Armed Services Committee last week, "that is true irrespective of what happens on the prosecution side. ... If a review panel has determined this person is a security threat [and] if for some reason he is not convicted for a lengthy prison sentence ... we would have the ability to detain him."

It's hard to imagine a situation in which the government thinks it has enough evidence to convict someone on terrorism charges but doesn't think he poses "a security threat." Since only guilty verdicts count, Obama might as well go directly to "prolonged detention" by presidential order, except that would reveal how little difference there is between him and his predecessor in this area.

Although Obama faults the Bush administration's "ad hoc legal approach," he, too, is leaving his options open. "We are indeed at war with Al Qaeda and its affiliates," he says. The implication is that anyone accused of ties to Islamic terrorism -- which could mean anything from undergoing training or planning an attack to donating money or building a website -- can be treated as a prisoner of war, held without trial until the "cessation of hostilities" (in effect, forever). Alternatively, he can be tried by a military commission for violating the laws of war, or he can be tried in federal court on a charge such as providing material support for terrorism.

"In our constitutional system," Obama says, "prolonged detention should not be the decision of any one man." Yet under the principles he and his underlings have laid out, the choice of how to treat a given terrorism suspect -- whether apprehended here or abroad, on a battlefield or off, now or in the future -- is entirely up to him.

In the end it may not matter much. When freedom is not a real possibility, due process is just for show.