The Metropolitan police have launched a criminal investigation sparked by "tens of thousands" of pages of data seized from David Miranda at Heathrow Airport, their lawyer Jonathan Laidlaw QC said.
The QC told the court that the police were only "partway through" examining the data.
That which has been inspected contains in the view of the police highly sensitive material, the disclosure of which would be gravely injurious to public safety and thus the police have now initiated a criminal investigation.
I am not proposing to say anything else which may alert potential defendants here or abroad to the nature and the ambit of the criminal investigation which has now begun.
There is an absolutely compelling reason to permit this investigation to continue.
The independent reviewer of terrorism legislation said he will examine the detention of David Miranda at Heathrow Airport.
Nick Clegg has backed David Cameron's decision to send a top civil servant to The Guardian to urge them to destroy classified data.
The Guardian journalist whose partner was held at Heathrow Airport hits out at the UK as he gives ITV News his first British TV interview.