The legality of the detention of David Miranda is still before the courts (there have only been interim hearings so far). My view is that the detention was likely to have been unlawful – and this also is the opinion of Charles Falconer, a former minister who helped introduce the relevant legislation.
However, the leading legal blogger Carl Gardner takes a different view.
Nonetheless, there is consensus that the key legal issue is whether the UK government used its Schedule 7 power of detention for its proper statutory purpose. For, as David Anderson - the independent reviewer of terrorism legislation who is also investigating the Miranda case – said in a 2012 report (at paragraph 10.63):
…gathering intelligence [is] an important by-product of the Schedule 7 examination, albeit one that can never serve as the prime motive for a stop.
One thing in Naomi’s posts which was especially eye-catching about the use of Schedule 7 is her mention of a sentence being deleted “for legal reasons” from a Guardian piece by the deputy prime minister.
The archived version shows that the original published piece had the words:
The intent behind detaining Miranda was the same: to retrieve or destroy classified information.
But the current version omits those words, and says at the end:
This article was amended on 23 August 2013 after a request from the deputy prime minister’s office based on legal reasons.
Anyway, let’s see what the High Court says about all of this. The substantive hearing is due in October.