Just compare how many convictions civilian courts have gotten to how many military tribunals have. The facts show quite clearly that it is in the civilian courts that convictions are actually more likely. They read the underwear bomber his rights and he told us everything. When the Bush administration tortured their prisoners those prisoners quit giving useful information.
Last I checked, civil courts had only convicted fourteen terrorists with ties to Al Qaeda, including Zacharias Moussaoui, shoe-bomber Richard Reid, Brooklyn Bridge bomber Iyman Faris, six Yeminis in upstate New York, Masoud Khan (who sought to fight US forces with the Taliban) and Johnny Jihad Lindh.
Almost fifty either had the charges dropped, were acquitted, were deported, or were given probation. Given the nearly 400 terrorism-related cases handled in civilian courts, the average sentence was only 11 months.