The ruling came in a lawsuit brought by conservative activist Larry Klayman, a user of Verizon mobile who had challenged the NSA's collection of metadata on his behalf and that of a client.
The NSA had ordered Verizon - one of the largest phone companies in the US - to disclose to it metadata, including telephone numbers, calling card numbers and the serial numbers of phones, of millions of calls it processes in which at least one party is in the US.
The judge ruled the plaintiffs had demonstrated “a substantial likelihood of success on the merits of their Fourth Amendment claim and that they will suffer irreparable harm absent...relief”, referring to the clause in the US constitution that bars unreasonable search and seizure by the government.
