NSA 'unconstitutional' surveillance ruling 'difficult for White House'
16 December 2013 Last updated at 22:47 GMT
A US judge has ruled the National Security Agency's mass collection of telephone data unconstitutional.
Former NSA General Counsel Stewart Baker said the result was "not inconceivable" but that the tone of the ruling - by a conservative, Federal District Judge Richard Leon - was "deeply confrontational - almost celebratory".
He told the BBC's Katty Kay that the government could win an appeal but that the litigation involved would be a "burden" and could cause problems for the administration for "some months or even years to come".