In the first hearing on the government’s justification for holding detainees at the Guantánamo Bay detention camp, a federal judge ruled Thursday that five Algerian men were held unlawfully for nearly seven years and ordered their release.

The judge, Richard J. Leon of Federal District Court in Washington, also ruled that a sixth Algerian man was being lawfully detained because he had provided support to the terrorist group Al Qaeda.

The case was an important test of the Bush administration’s detention policies, which critics have long argued swept up innocent men and low-level foot soldiers along with high-level and hardened terrorists.