The US Department of Homeland Security issued an “Information Bulletin” concerning “Photographing the Exterior of Federal Facilities” last year. The New York Times passed along the bulletin last week when it obtained a redacted version.
There are a couple of salient points relating to photographers’ right outlined within the bulletin, which we already knew of course. First, the bulletin notes that the Code of Federal Regulations specifically allows for photographers to take photos inside federal buildings.
Second, and perhaps more importantly, the bulletin reiterates the pre-existing law by noting that “absent reasonable suspicion or probable cause, law enforcement and security personnel  must allow individuals to photograph the exterior of federally owned or leased facilities from publicly accessible spaces.”
For those unfamiliar with standards of proof in criminal law, reasonable suspicion requires facts or circumstances that would lead a reasonable police officer to believe that criminal activity is afoot. Once reasonable suspicion is present, the officer is within his right to conduct a Terry-stop, which is a brief detainment for further investigation and generally includes a cursory pat down of the suspect’s body.
Probable cause requires facts or circumstances that would lead a reasonable person to belief that a person has committed a crime. Once probable cause is present, a police office can make an arrest for a crime and conduct a search incident to arrest of the person and belongs in his immediate possession.
Outside of probable cause or reasonable suspicion, law enforcement has no right to detain or interfere with a photographer taking photos of a federal building from the sidewalk or other public area.