[TheOtherHobbes]

In fact all non-establishment groups - CND, anti-nuclear power protesters, anti-globalisation protesters, trade unions, animal rights activists, UK's own Occupy movement, anarchists, even worthy intellectual left-leaning blogs, and so on - were and are routinely infiltrated and manipulated.

There's nominal press freedom, in that it's possible to call politicians rude names.

But if your movement or leaders become powerful enough to have a hope of influencing policy and to challenge establishment cash flows and power relationships, expect some blow back.

[samscully]

Fortunately the non-establishment groups sometimes infiltrate and manipulate the establishment too [1].

[1] http://www.theguardian.com/politics/2015/oct/17/jeremy-corby...

[dmix]

Highly unlikely this happens very often at all. Counter-intelligence by the FBI (the primary intel agency dealling with domestic political organizations) is very thorough. It would take an extremely skilled person to get through their interviews, background checks, mandatory polygraph tests, etc.

The FBI are the best trained people in the world at eliciting information from people unwillingly/unknowingly - which is enough of a barrier on it's own.