Nat Hentoff explains it all for the Progressive:

The Terror of Pre-Crime

Keep in mind the massive, pervasive electronic surveillance–with minimal judicial supervision under the USA Patriot Act–of inferential “pre-crime” conversations and messages, both sent and received. Add to that the FBI’s power, under the same law, to break into your home or office, with a warrant, while you’re not there, and inset “The Magic Lantern” into your computer to record every one of your keystrokes, including those not sent. Then add the Patriot Act’s allowing the FBI to command bookstores and libraries to reveal the books bought or read by potential domestic terrorists.

Here’s the text of the entire article in case the link goes bad:
http://www.progressive.org/sept02/hen0902.html
September 2002
Ashcroft Watch Nat Hentoff
The Terror of Pre-Crime
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Nat Hentoff photoJohn Ashcroft recently released his guidelines for investigating people he suspects as terrorists, and these guidelines exceed even J. Edgar Hoover’s contempt for due process.
Activists particularly–and I expect the term applies to a good many readers of The Progressive–should know what may well be in store for them. On page three of “The Attorney General’s Guidelines on General Crimes, Racketeering Enterprise and Terrorism Enterprise Investigations,” we are told: “A terrorism enterprise investigation may be initiated when facts or circumstances reasonably indicate that two or more persons are engaged in an enterprise for the purpose of . . . furthering political or social goals wholly or in part through activities that involve force or violence and a federal crime . . .”
Note the use of “reasonably” and “wholly or in part.” These insidiously malleable guidelines for terrorism investigations could apply to political action (and the reaction) during demonstrations by environmentalists, anti-globalizationists, animal rights pickets, or union members on strike, as well as pro-lifers trying to talk, and only to talk, to women entering abortion clinics (“obstruction” at clinics can be a federal crime).
The guidelines go on to note that “the ‘reasonable indication’ standard for commencing a terrorism enterprise investigation is . . . substantially lower than probable cause.” It is so low it could be part of the new Steven Spielberg-Tom Cruise movie, Minority Report, which envisions the nabbing of “pre-criminals.” As The Washington Times puts it, such pre-criminals are convicted “before they ever act on, or, in some cases, are even aware of, their murderous designs.”
On page four of the Ashcroft Guidelines: “The nature of the conduct engaged in by a [terrorist] enterprise will justify an inference that the standard [for opening a criminal intelligence investigation] is satisfied, even if there are no known statements by participants that advocate or indicate planning for violence or other prohibited acts.” (Emphasis added.)
The Attorney General, furthermore, extends the dragnet to make individuals in a group under suspicion responsible for what other members say or write: “A group’s activities and the statements of its members may properly be considered in conjunction with each other. A combination of statements and activities may justify a determination that the threshold standard for a terrorism investigation is satisfied, even if the statements alone or the activities alone would not warrant such a determination.” (Emphasis added.)
Also indicating the “pre-crime” mindset of Attorney General Ashcroft is the following paragraph. “While no particular factor or combination of factors is required, considerations that will generally be relevant whether the threshold standard for a terrorism investigation is satisfied includes as noted, a group’s statements, its activities, and the nature of potential federal law violations suggested by its statements or its activities.” (Emphasis added.)
Keep in mind the massive, pervasive electronic surveillance–with minimal judicial supervision under the USA Patriot Act–of inferential “pre-crime” conversations and messages, both sent and received. Add to that the FBI’s power, under the same law, to break into your home or office, with a warrant, while you’re not there, and inset “The Magic Lantern” into your computer to record every one of your keystrokes, including those not sent. Then add the Patriot Act’s allowing the FBI to command bookstores and libraries to reveal the books bought or read by potential domestic terrorists.
You may now appreciate the prophecy of Senator Frank Church–who was instrumental in exposing the constitutional crimes of J. Edgar Hoover’s Cointelpro operation–when he said in 1975 that future government intelligence capabilities could “at any time be turned around on the American people, and no American would have any privacy left–such is the capacity to monitor everything, telephone conversations, telegrams, it doesn’t matter.” And that was before the omnivorous, permeable Internet. The Web can be a spider web.
Senator Church, referring to “potential” enemies of the state, warned: “There would be no way to fight back because the most careful effort to combine together resistance to the government, no matter how privately it was done, is within the reach of the government to know.”
There is still time to fight back.
Nat Hentoff is a columnist for The Village Voice, Legal Times, Editor&Publisher, and The Progressive.