Birkett Report, Cmnd 283 (Oct. 1957).
This report was the result of an inquiry into the interception of communications by the Committee of Privy Councillors. It provides an account of the grounds upon which an application for a warrant could be made at that time.
The report stated the principles governing the issue of warrants to the Security Service as follows:
- (a) There must be a major subversive or espionage activity that is likely to injure the national interest;
- (b) The material likely to be obtained by interception must be of direct use in compiling the information that is necessary to the Security Service in carrying out the tasks laid upon it by the State; and
- (c) Normal methods of investigation must have been tried and failed, or must, by the nature of things, be unlikely to succeed if tried.
Less stress was laid upon the need for the Security Service to secure convictions, due to the nature of its duties in safeguarding the State.