No laws in the United States require signs to be posted when video surveillance cameras are installed in a public place. Only 13 states have any laws restricting use of hidden cameras, primarily banning them where privacy is expected.
No laws in the United States require signs giving notice of hidden camera surveillance, particularly when surveillance takes place in a public setting where citizens have no expectation of privacy. Surveillance cameras, such as nanny cams placed in homes to monitor household employees, also require no posting of signs.
Federal laws do prohibit hidden cameras in places where citizens have a reasonable expectation of privacy, such as bathrooms, hotel rooms, changing rooms and changing rooms. In workplaces where employment contracts include a clause requiring employees to consent to surveillance, employers often reinforce that agreement with a sign warning that surveillance cameras are operating.
Posting a sign warning of video surveillance can be such an effective deterrent to crime that some people post the sign even where they have imitation, nonfunctional surveillance units or no video camera in place at all.
Posting a sign to inform visitors or employees of video surveillance not only provides a measure of protection from crime, it also allows the homeowner or business owner who installs the cameras to argue that anyone caught on camera was warned in advance.