The American government’s indiscriminate gathering of its citizen’s phones records is “almost Orwellian” and probably unconstitutional a US district court judge has found in a decision likely to be appealed by the administration which says the surveillance is crucial to its national security efforts.

The US district court judge Richard Leon found that the National Security Agency’s phone surveillance program was likely to fall foul of the constitutional ban on unreasonable searches and seizure.

“I cannot imagine a more ‘indiscriminate’ and ‘arbitrary’ invasion than this systematic and high-tech collection and retention of personal data on virtually every single citizen for purposes of querying and analysing it without prior judicial approval,” Judge Leon wrote. “Surely, such a program infringes on ‘that degree of privacy’ that the founders enshrined in the Fourth Amendment.”

The case against the NSA activities was bought by a conservative legal activist, Larry Klayman, after details about the program were leaked by Edward Snowden, a former contractor who has since taken temporary asylum in Russia.