“The Bush administration used the criminal justice system to convict more than 300 individuals on terrorism-related charges,” writes Attorney General Eric Holder in a new letter to Republican critics in Congress. The letter is part of the Obama administration's aggressive defense of its decision to grant full American constitutional rights to al Qaeda soldier Umar Farouk Abdulmutallab, the accused Christmas Day bomber. That defense boils down to one sentence: Bush did it, too.Republicans on Capitol Hill object. They argue that one of the reasons some terrorists were handled in the criminal justice system is that it took George W. Bush and Congress years to establish a military tribunal system that satisfied constitutional requirements — a process that was lengthened by legal challenges filed by some of the same lawyers who now work in Holder's Justice Department.You can argue about that forever. But there's one serious factual debate going on about Holder's letter, and that concerns those “300 individuals.” Just who are they?It turns out some lawmakers have been trying for months to get an answer. They're not saying the claim is false — they just want to see what it's based on. But so far they haven't been able to find out.It started back in May 2009, when President Obama gave his famous National Archives speech outlining the plan to close the Guantanamo Bay terrorist detention center. “Bear in mind the following fact,” Obama said. “Nobody has ever escaped from one of our federal 'supermax' prisons, which hold hundreds of convicted terrorists.” Although the president did not put a number on it, various figures, ranging up to 300, have been tossed around in the months since.