Washington ? For the first time in the nearly three years since the Sept. 11 attacks, a prisoner picked up as a potential terrorist and held nearly incommunicado at a U.S. prison in Cuba got a chance Friday to convince his jailers that he should go free.

The hearing at the Navy prison camp at Guantanamo Bay, Cuba, is the government’s most visible response since a Supreme Court ruling last month granted new legal rights to about 600 foreign-born men held at the U.S. base on Cuba’s southeastern tip.

Separately Friday, the Justice Department filed its first detailed response to lawsuits from Guantanamo detainees. The detainees have no constitutional rights, including the right to see a lawyer, the government said in federal court filings.

The Supreme Court’s ruling gave the Guantanamo prisoners a means to challenge their captivity in federal court, and the government will allow outside lawyers to help them, but that does not mean that wider constitutional protections apply, government lawyers wrote.

“As aliens detained by the military outside the sovereign territory of the United States and lacking a sufficient connection to this country, petitioners have no cognizable constitutional rights,” the lawyers said in court papers.

Civilian defense lawyers can visit their clients at Guantanamo under careful restrictions, the Bush administration said. Lawyers must have security clearances and some lawyer-client meetings may be monitored by government agents, the filing in U.S. District Court said.

“These necessary precautions do not compromise attorney-detainee communications,” the government lawyers wrote.

At the Pentagon, Navy Secretary Gordon England said the hearing into whether the Navy was properly holding an unidentified prisoner as an enemy combatant was the first of some 600 to be held over the coming one to four months.

The administrative hearing was closed to the press and the public.