According to the Christian Science Monitor, the six "eco-terrorists" caught by the FBI are thought to belong to the Earth Liberation Front/Animal Liberation Front. To get some idea of what ELF/ALF has been up to, take a look at the Southern Poverty Law Center's interesting selection of ELF/ALF attacks up to 2002.
Besides blowing up labs and burning SUVs, ELF/ALF actiivities are provoking politicians to propose legislation that abridges freedom of speech and gives the police more power to stifle dissent. For example, ACLU lawyer Larry Frankel, testifying before the legislature in Pennsylvania in June 2005, noted that a proposed anti-eco-terrorism bill "violates the First Amendment because it authorizes greater penalties for defendants with certain disfavored political views."
Frankel illustrated how this would work:
People who protest outside of an animal research facility and block the entrance to that facility may be considered eco-terrorists. On the other hand, people who protest outside of a weapons-manufacturing plant and block the entrance to that facility will not be subject to enhanced penalties even though they are engaged in essentially similar activities.
Even if this bill were deemed to be consistent with the First Amendment, we cannot understand why Pennsylvania would want to characterize as terrorists individuals who engage in conduct that only amounts to summary offenses or misdemeanors. Classifying people who trespass or engage in disorderly conduct as terrorists is unwarranted. Imposing harsh sanctions on people who commit civil disobedience is a ploy that was used against civil rights protestors. It is a coercive tactic that one would not expect in a society that not only considers itself free but also holds itself out as a model for other societies.
We don't need to have special eco-terrorism statutes. We already have plenty of laws against vandalism and arson. Now go catch the bastards before they blow up another lab!