Padilla has been barred from meeting with lawyers since his arrest May 8. U.S. District Judge Michael Mukasey said Wednesday that Padilla may meet with them now.
The ruling was a blow to the government, which had argued that Padilla, a U.S. citizen, had no right to challenge its actions in court because he was detained as an "enemy combatant."
"I think it's almost certain the government will appeal the ruling in the Padilla case to the 2nd U.S. Circuit Court of Appeals," reports CBSNews.com Legal Analyst Andrew Cohen. "And either the appeals court will go along with the government and stay things for a while, or it will back the trial judge, which will create a conflict between the 2nd and 4th Circuits that probably will spur the United States Supreme Court to get involved.
Padilla was arrested on a material witness warrant issued by a grand jury and secretly held in a federal jail. He has been in a Navy brig since he was declared an "enemy combatant" in June and transferred to the control of the U.S. military. The government says the "enemy combatant" declaration allows it to hold him without formal criminal charges.
The government said Padilla twice met with senior al Qaeda operatives in Pakistan in March and discussed a plot to detonate a radiological weapon in the United States.
A spokesman for U.S. Attorney James B. Comey had no immediate comment. Lawyers for Padilla did not immediately return a telephone message for comment.