The key thing to remember here is that the Fourth Amendment's protections require probable cause of a crime and a warrant in order to search someone's person or property. But attending a public meeting? Fair game, according to the law. Nonetheless, most people expect the police to exercise more discretion, and not actually send out undercover officers to spy on peaceful activists without something actually illegal to investigate.
Police have acknowledged that the monitoring, which took place during the administration of then-Gov. Robert L. Ehrlich Jr. (R), spiraled out of control, with an undercover trooper spending 14 months infiltrating peaceful protest groups. Troopers have said they inappropriately labeled 53 individuals as terrorists in their database, information that was shared with federal authorities. But the new documents reveal a far more expansive set of police targets and indicate that police did not close some files until late 2007.
The surveillance ended with no arrests and no evidence of violent sedition. Instead, troopers are preparing to purge files and say they are expecting lawsuits.