In the 1970s, COINTELPRO was exposed. Under J Edgar Hoover, the FBI had infiltrated civil rights groups, blackmailed and then assassinated Martin Luther King, incited lone activists into violence so they could be arrested, provided bombs to peace groups, and then arrested members of the group for "approving" the use of the bombs. The Nation of Islam was completely infiltrated and leadership taken over by the FBI. It was a big embarrassment.
The program was supposed to end, but it continues to this day. Agents provocateurs are creating violent incidents at Occupy rallies. Older women at church-based peace groups find FBI agents in their midst, posing as activists.
Veterans for Peace is challenging the spying and infiltration in court.
Here's an article about the sordid history of the FBI in the height of the Civil Rights movement.
This article begins with the history of FBI infiltration of a peace group that was organizing opposition to the School of the Americas, which trains terrorists to overthrow democratically-elected governments in Latin America that are not sufficiently friendly to US business interests. The article goes on to talk about environmental groups that experience the same treatment. It ends with some guidelines: how you might detect an FBI agent in the midst of your group.
I have often asked, "Why don't we have an effective anti-war movement in America today? What happened to the Peace and Love hippies who marched on Washington to end the Vietnam war, and the Yippies who turned out in force at the 1968 Democratic convention, after Robert F Kennedy was murdered and the other peace candidate, Gene McCarthy, was maneuvered ouf of the nomination? Part of the answer is that the nation's most powerful anti-crime bureau has been re-purposed to stifle free speech and keep progressives out of the Democratic party.
None of this is legal. It is warrantless search, in violation of the 2nd Amendment. Its entire premise is the throttling of free speech as guaranteed by the 1st Amendment.
"Information warfare" has become ubiquitous and devastatingly sophisticated.
I think it's a tactical necessity that before we can make progress in the peace and environmental movements, we have to call out the FBI for suppression of our nonviolent, legitimate protests.