The Supreme Court is leaving in place the conspiracy conviction of Osama bin Laden’s former personal assistant by a military tribunal.

The justices’ order Tuesday was issued without comment and could be the final legal appeal by Guantanamo detainee Ali Hamza al-Bahlul.

A military commission convicted Bahlul of conspiracy and other crimes in 2008.

An appellate panel at one point ruled the military tribunal lacked the authority to convict defendants of conspiracy and other crimes that are not international war crimes.

But the U.S. Court of Appeals for the District of Columbia Circuit later upheld the conviction.