In a victory for civil liberties groups and online activists, a federal judge in Philadelphia issued a temporary restraining order Thursday that bars the government from enforcing a new law designed to protect minors from indecent material on the Internet.

Thursday's ruling prohibits the Justice Department from enforcing the recently passed Child Online Protection Act, which was scheduled to go into effect today and would have imposed sweeping new restrictions on any commercial site that distributes content that might be considered harmful to minors.

Civil liberties groups filed a suit challenging the constitutionality of the act last month, and in issuing Thursday's ruling, Judge Lowell A. Reed determined that the plaintiffs had "shown a likelihood of success on the merits of at least some of their claims."