Federal courts have ruled that Omar Deghayes and hundreds of other prisoners in Guantanamo Bay do not have the right to challenge their custody.
The former student from Saltdean lost a petition in the US Court of Appeals to challenge President George Bush's right to hold nearly 400 prisoners without charge.
Louise Purbrick, of the Save Omar campaign, said: "This overturns one of the oldest civil rights laws in the world. I don't understand how they could come to this decision.
advertisement "Obviously for us it's a real blow but it doesn't make us think we're not going to get him out. We'll keep on going, come what may, because the direction of our work is now focused on the British Government."
In its two to one decision, the Court of Appeals for the District of Columbia upheld the Military Commissions Act - stripping Guantanamo detainees of their right to habeas corpus petitions.
Lawyers for the detainees vowed to quickly petition the US Supreme Court to again address the issue of Guantanamo.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article