The administration claims the crackdown on ANTIFA is an effort to reduce violence and destruction coming in the wake of the murder of George Floyd in Minneapolis.
Federal statute defines domestic terrorism as violence committed to intimidate a specific population, although there is no additional sentencing penalty. The F.B.I usually works within individual local jurisdiction to intercept, prevent, and charge suspected terrorists.
While the DOJ can technically investigate damage to federal government property and assault on federal officers (which may have happened since protests erupted although there are few reports of federal property damage), there’s no law or authority that can be used currently to make such a declaration. It can only be done with an international organization like Boko Haram or ISIS.
Democrats routinely criticized this fact, since the limitations of the statute also keep suspected right-wing terrorist groups from being prosecuted in this manner.
Additionally, critics will argue that ANTIFA is not a group of individuals, rather a movement with a set of common beliefs loosely affiliated with no leaders or official membership and that proving or an affiliation ANTIFA would be difficult and may present constitutional privacy violations.