British police have opened a criminal probe into the materials seized from the partner of journalist Glenn Greenwald at a London airport. David Miranda was on his way home to Brazil when he was held for nine hours under a British anti-terrorism law. He faced repeated interrogation and had many personal items seized, including thumb drives carrying information used by Greenwald in his reporting on NSA surveillance. On Thursday, a British court ruled investigators can probe Miranda’s seized data for alleged links to terrorism, but not for criminal activity. Miranda attorney Gwendolen Morgan called the ruling a partial victory.

Gwendolen Morgan: “The court accepted today that in order for the Home Office and police to look at that material there has to be a genuine threat to national security. The Home Office and police now have seven days to prove that there is a genuine threat to national security rather than make mere assertions as they have done today. The undertakings that the police sought were stopped in their tracks, and some of the basis on which the police sought to justify their position was roundly rejected.”

The British government has been given one week to pore through Miranda’s seized files.