In a setback for the Bush administration, US District Judge Joyce Hens Green on Monday also ruled the prisoners at the US military base at Guantanamo Bay in Cuba have constitutional protections under the law.
"The court concludes that the petitioners have stated valid claims under the Fifth Amendment to the United States Constitution and that the procedures implemented by the government to confirm that the petitioners are 'enemy combatants' subject to indefinite detention violate the petitioners' rights to due process of law," Green wrote.
More than 540 suspects are being held at Guantanamo after being detained during the 2001 invasion of Afghanistan and in other operations in the US "war against terrorism." They are suspected of being al-Qaida fighters and/or Taliban fighters.
Bush administration attorneys argued the prisoners have no constitutional rights and their lawsuits, challenging the conditions of their confinement and seeking their release, must be dismissed.
The detainees are suspected
al-Qaida and Taliban fighters
The tribunals, formally called a military commission, at the base were authorised by President George Bush after the 11 September 2001, attacks, but have been criticised by human rights groups as being fundamentally unfair to defendants.
Green's 75-page opinion was the unclassified version made available for public release. It stemmed from 11 cases involving Guantanamo prisoners.
Her ruling probably will not be the final word on the issue.
A different federal judge in Washington, DC, on 19 January dismissed the cases of seven Guantanamo prisoners on the grounds that they have no recognisable constitutional rights and are subject to the military review process.
The cases could be appealed to the US appeals court, and then ultimately to the US Supreme Court.