From the New York Times:
The defendant, Ahmed Khalfan Ghailani, the only former Guantánamo detainee to be tried in the civilian court system, had appealed his 2010 conviction on grounds that his detention amounted to an unconstitutional delay in bringing him to trial.
The panel acknowledged that the nearly five-year delay was substantial. But, it said, “the Supreme Court has repeatedly held that the government may purposely delay trials for significant periods of time, so long as, on balance, the public and private interests render the delay reasonable.”
Which is to say that, on balance, the constitutional right to a speedy trial no longer exists.