From Washington Post (link):
The Supreme Court yesterday declined to expedite the case of two Chinese Muslims who have been held for four years at the U.S. prison at Guantanamo Bay, Cuba, despite being cleared of ties to terrorism. The justices, without comment, deferred to a federal appellate court that is scheduled to hear the pair’s plea for release next month.
Uighurs have been agitating against the Chinese government and want to establish their own nation in Xinjiang province, which they call East Turkistan. The prisoners, considered terrorists by China, do not want to return to their homeland, where they would be likely to be imprisoned and tortured.
See also Wikipedia’s “East Turkestan independence movement”
And “East Turkestan Islamic Movement” by Council of Foreign Relations