Originally, al-Marri was charged by John Ashcroft under Federal criminal law. Pres. Bush overruled him; the charges were dismissed and al-Marri was detained under the President's executive order. The Obama administration may reverse course and attempt to restore the criminal prosecution as Lyle Denniston reports here.

Court trial for Al-Marri?
Thursday, February 26th, 2009 2:25 pm | Lyle Denniston
....
The American Civil Liberties Union, citing news stories, reported Thursday that the Justice Department will shortly file terrorism charges and hold a trial in civilian court of a Qatari national, Ali Saleh Kahlah Al-Marri — the only detainee taken prisoner in the U.S. and still being held in this country. ...
..... [a summary of the al-Marri proceedings follow] ....
The ACLU news release is here. The Washington Post story is here.

If the indictment is filed, the SCOTUS appeal, not far off from being decided, will probably be moot and dismissed (based on recent decisions). There may be problems in prosecuting in Federal court because of the prior dismissal of the original Federal charges (mentioned in prior posts); although the original charges (credit card fraud and making false statements to the FBI) are different from the new charges (providing material support to al-Qaeda).