Why whistle-blowers like Edward Snowden must use drastic measures

When the FBI was formally launched in the 1930s, its brief was to fight crime. But under J. Edgar Hoover it stretched much further beyond that until finally a US Senate investigation was ordered in 1975 to rein in its powers.

The group of people who broke into an FBI office in 1971, stole its files and alerted the media about the agency's activities has now identified themselves and recounted how they did it and why.

Unlike Edward Snowden, who last year leaked details of the National Security Agency's spy programmes, none of these eight people had access to the files - they had to break in to get them. What comes through from their various media interviews is their sheer determination and drive. They were all activists but none of them firebrand as you might imagine - just ordinary people, leading ordinary lives.

A taxi driver had to take a locksmith correspondence course to learn how to break locks, while one couple decided to join despite fears for their family of three children. They even made arrangements with other family members to raise them if they were caught and jailed.