Yes, detainees are given fair trials and rights in secret courts, because their trial rights are proportional to their offenses. When someone perpetuates an act of war on the United States, they do not have the same criminal trial rights as someone who commits an offense against another person. As such, their rights are fairly represented in secret tribunals.
Detainees, especially those at Guantanamo Bay, aren't given rights or a fair trial in secret terror courts if the resuts are secret. The detainees haven't been given due process at all for a "speedy trial." Of course, they aren't American citizens and the U.S. Constitution may not apply to foreigners. The trials shouldn't be secret in light of international laws prohibiting unfair justice or torture.