Sorry, but I have to agree with some previous posters. The ALF and their fellow travelers are most certainly guilty of trespass, theft, malicious destruction, and endangerment, and they should be prosecuted for those specific crimes, but they are not terrorists.
People who steal and release other people's cows are simply not equatable with people who fly other people's airliners into skyscrapers.
To equate them marginalizes the actions of mass murderering hijackers and does a huge disservice to the Patriot Act and the War on Terror.
They fit the classic definiton of terrorist.
The use of violence and threats to intimidate or coerce, especially for political purposes.
They were defined as terrorists before 9/11.