The Obama administration has begun to back away from its plans to bring the 9/11 plotters to trial in New York City. Mayor Michael Bloomberg, an erstwhile supporter of the trial, changed his mind on grounds that it would be too risky and too costly. Lawmakers from both parties began voicing opposition. Sen. Lindsey Graham (R., S.C.) and Rep. Frank Wolf (R., Va.) threatened to introduce legislation de-funding the transfer of the plotters from Gitmo to New York. To relieve the pressure, the president ordered the Justice Department to consider another location for the trial. But the pressure will not go away. It is hard to imagine any urban mayor agreeing to host the trial now that Bloomberg has refused. And the concept of civilian trials for enemy combatants is irredeemably flawed, for reasons we catalogued in a previous editorial. The administration nevertheless seems determined to hold the trial in the United States, and Congress might need to step in to prevent this from happening. De-funding detainee transfers on a case-by-case basis, however, is not the right approach. Withholding the funding for the transfer of the 9/11 plotters (mastermind Khalid Sheikh Mohammed is among them) from Gitmo to New York City would stop this trial from happening, but it would leave undecided the larger question of how and where enemy combatants should be tried. There is a simple enough answer to this question: Congress should pass a law mandating that anyone designated an enemy combatant by the relevant tribunal must be tried in a military commission, and not in the federal courts. This would take the decision out of the hands of Obama’s Department of Justice — which, given its track record, would be a very good thing. By contrast, withholding funding on a case-by-case basis leaves it to members of the political class to arbitrarily decide the disposition of each case. Such an approach makes a mockery of the due process that Obama’s apologists claim to care about: No administration is going to bring a terrorist to trial here if there is even a remote chance of his being acquitted and released into the population. These would be show trials, pure and simple. Under Obama’s plan, military commissions would be reserved for cases that would be harder to win in federal court. Indeed, this is reportedly why the administration plans to use the commissions to try at least five detainees, including one of the plotters of the attack on the U.S.S. Cole. Congress needs to take this problem off the president’s hands by issuing new guidance on the jurisdiction of the federal courts. If the Democrat-controlled Congress cannot bring itself to issue such a stern rebuke of the president’s policy, then it should de-fund any and all detainee transfers into the United States for now — wobbly Dems could call it a “wait and see” approach — thus taking away the president’s power to bring terrorists to trial on American soil. If it’s too expensive and dangerous to have this trial in New York City, it’s probably not a good idea to have it anywhere in the United States, including military bases where, lest we forget, soldiers’ families live. Gitmo is the right place to try these combatants, and a military commission is the right tool for the job. If the president refuses to do the right thing, Congress can — and should.