So much for parliamentary privilege: Damian Green, the frontbench Conservative MP for Ashford, was arrested this week and held for nine hours for his part in leaking official documents to the press. The police's absurd over-reaction shows a lack of understanding of political sensitivities in relation to freedom of information.

The government is right to investigate leaks. Given the sensitivity of materials in the Home Office, police involvement can be appropriate. In this case, however, there were no security implications. The mole should simply have been subject to internal disciplinary procedures.