Contents Subject Page Letter to the Prime Minister iv Introduction 1 Functions of the Commissioner 1 Discharge of my functions 1 The extent of interception: General 4 Safeguards 4 Communications data 4 Prisons 5 Foreign and Commonwealth Office and Northern Ireland Office Warrants 6 The Investigatory Powers Tribunal 6 Assistance to the Tribunal 7 Errors 7 Conclusion 10 Statistical Annex 11 iii