The radical animal rights movement has been labeled a terrorist movement by federal law enforcement and elected officials, and there have been laws passed making direct action in the name of animal rights a federal offense of domestic terrorism. This dissertation explores the ways in which terrorism has been socially and politically constructed to marginalize the animal rights movement, to the benefit of powerful and well connected interests. I do this by comparing the radical animal rights and extreme anti-abortion movements, especially in the ways each gets labeled by federal law enforcement. The animal rights movement is more likely to be referred to as a terrorist movement, even though the extreme anti-abortion movement has been responsible for the murders and assaults of health clinic workers and doctors. This in spite of the fact that no one has been physically harmed by the animal rights movement. I examine the ways in which the pharmaceutical and bio-medical industries have been able to get laws passed, at both the state and federal levels, criminalizing animal rights activism. I also explore the various ways animal rights activists have faced political repression based on their political beliefs, as well as the response of animal rights activists and civil liberties lawyers to this form of state repression.