Every country and state has its spy camera laws, and it is up to you as a hidden spy camera user to know your nation or state's law concerning such devices. In the United State of American, most video recordings are considered legal with or without permission. There are however several laws existing concerning 'Invasion of Privacy' which relates to the concept of 'expected privacy' and includes areas where a person may expect a certain level of personal privacy like in locker rooms, bathrooms, dressing rooms, bedrooms, other rooms where a high level of confidentiality kept.
Most laws regarding video recording privacy matters allow covert video recording and monitoring of activity with the aid of spy cameras under most scenarios without notification of the parties engaged, however, it is still recommended that before using a spy camera, you should refer to your local law enforcement first. Despite having a basic understanding of the law, you still need to ensure that you are complying with all local and federal rules before using spy cameras for video monitoring or surveillance.
Some spy cameras have an incorporated microphone which can record audio. There are specific laws that govern audio recording and voice tapping. Violation of any of these regulations can land you up in deep trouble. There are a couple of situations defined for audio recording. They are "One Party Consent" and "Two Party Consent". "One party consent" means, only the person recording the conversation has to give his permission, and it is not needed to notify the other party/parties involved. On the other hand "two-party consent" means that the person recording must inform all the persons involved that the conversation is being tapped.
Once a spy cam has taped the photos, there are no clear laws to regulate the storage and use of monitoring tapes. Digital technology now allows you to store such information almost indefinitely and this could be an area concern as the video footage could fall into the wrong hands.
In a nutshell, use of spy cams for video recording is legal in all 50 states since it is done for legitimate purposes. It is still a smart idea to go local laws regarding precisely what you are recording before doing so, to be sure you are working within legal preferences.