ATLANTA—On a recent March morning, a large monitor at the front of a DeKalb County courtroom flickered to life as Superior Court Judge David B. Irwin appeared over Zoom. The hearing—with attorneys and out-of-state defendants joining remotely—centered on a question with national implications: Can activists who protested Atlanta’s controversial police training center be prosecuted as domestic terrorists? The case has stretched on for nearly three years, outlasting both the clearing of the forest and the opening of the training center. Protests against the Atlanta Public Safety Training Center, dubbed “Cop City” by critics, sparked the charges. If upheld, protesters could...