"When he struck down the military commission process at the US-run Guantánamo prison camp in June, Supreme Court Justice John Paul Stevens reached back into history to cite the kind of unfair trial that might result under the Bush administration's plan to use a sharply streamlined system of justice to prosecute suspected Al Qaeda terrorists as war criminals.
His example: the 1945 trial of Japanese Gen. Tomoyuki Yamashita by a special US military commission in the Philippines. The commission held the general responsible for war crimes committed by forces under his command, although no direct evidence was presented during the month-long trial to show that he had ever ordered, participated in, or condoned the atrocities. He was subsequently hanged.
That outcome was made possible, in part, through liberal use of hearsay evidence. The military commission was told it was free to use as evidence anything that its members felt would be of assistance to a reasonable person in proving or disproving the charge.
"Every conceivable kind of statement, rumor, report, at first, second, third, or further hand, written, printed, or oral, and one 'propaganda' film were allowed to come in" as evidence, wrote then-Supreme Court Justice Wiley Rutledge in a criticism of the proceeding.
...
"It is imperative that hearsay evidence be considered' in trials of Guantanamo detainees." - US Attorney General Alberto Gonzales."
http://www.csmonitor.com/2006/0807/p02s01-usju.html