The partner of former Guardian journalist Glenn Greenwald who was held by authorities while travelling though Heathrow airport will launch a legal case against his detention today.

David Miranda has held for nine hours on 18 August as he transited through London on his way from Berlin to the couple’s home in Rio de Janeiro.

UK authorities stopped the 28 year old Brazilian under section 7 of the Terrorism act 2000 and seized a laptop, mobile phone, memory cards and dvds.