Last year, Attorney General Eric Holder Jr. described a federal court trial for the self-professed mastermind of Sept. 11 attacks, Khalid Shaikh Mohammed, as “the defining event of my time as attorney general.” On Monday, Mr. Holder’s dream for demonstrating the power of the American court system crumbled when he announced that the trial would take place not in New York City or anywhere in the United States but before a military commission at the Guantánamo Bay, Cuba, prison camp.

That retreat was a victory for Congressional pandering and an embarrassment for the Obama administration, which failed to stand up to it.

The wound inflicted on New York City from Mr. Mohammed’s plot nearly a decade ago will not heal for many lifetimes, yet the city, while still grieving, has thrived. How fitting it would have been to put the plot’s architect on trial a few blocks from the site of the World Trade Center, to force him to submit to the justice of a dozen chosen New Yorkers, to demonstrate to the world that we will not allow fear of terrorism to alter our rule of law.

But, apparently, there are many who continue to cower, who view terrorists as much more fearsome than homegrown American mass murderers and the American civilian jury system as too “soft” to impose needed justice. The administration of George W. Bush encouraged this view for more than seven years, spreading a notion that terror suspects only could be safely held and tried far from our shores at Guantánamo and brought nowhere near an American courthouse. The federal courts have, in fact, convicted hundreds of terrorists since 9/11. And federal prisons safely hold more than 350 of them.