Attorney General Eric Holder’s decision to try Khalid Sheikh Mohammed in a civilian court, as if he were a garden variety killer and not the mastermind of the terrorist attacks on Sept. 11, 2001, may go down in history as one of the most inept presidential decisions on a legal matter since Ike Eisenhower’s appointment of Earl Warren to the U.S. Supreme Court. And that is for a simple reason: It might result in Obama’s own political destruction.

That, at least, is the compelling assessment of columnist Pat Buchanan, who asks all the right questions in his column about the trial of Mohammed and four accomplices. To wit, a few excerpts:

“[I]f we are at war, why is Khalid Sheikh Mohammed headed for trial in federal court in the Southern District of New York? Why is he entitled to a presumption of innocence and all of the constitutional protections of a U.S. citizen?

“Is it possible we have done an injustice to this man by keeping him locked up all these years without trial? For that is what this trial implies — that he may not be guilty.

“And if we must prove beyond a reasonable doubt that KSM was complicit in mass murder, by what right do we send Predators and Special Forces to kill his al-Qaida comrades wherever we find them? For none of them has been granted a fair trial.

“When the Justice Department sets up a task force to wage war on a crime organization like the Mafia or MS-13, no U.S. official has a right to shoot Mafia or gang members on sight. No one has a right to bomb their homes. No one has a right to regard the possible death of their wives and children in an attack as acceptable collateral damage.

“Yet that is what we do to al-Qaida, to which KSM belongs. … [I]f we are at war, what is KSM doing in a U.S. court?”

Mr. Buchanan then offers a good history lesson in how men such as Mohammed, who offered to plead guilty before a military commission, are handled. Often, we simply shoot them because we are at war. Or they are tried before military commissions. They do not receive civilian justice.

More importantly, Mr. Buchanan and others have asked, what happens if Mohammed and his terrorist accomplices are found not guilty? What if the judge dismisses the case because Mohammed was tortured or did not receive a Miranda warning when he was “arrested?” And what if a conviction is overturned?

Messrs. Obama and Holder have opened a can of worms that could well doom this administration, but more importantly, could liberate one of this country’s most dangerous enemies. He is certainly its greatest mass murderer.

These two truths invite a question: Are Messrs. Obama and Holder prepared to set this man free? Perhaps they are.