While it&#x27;s legal to take someone&#x27;s photo in public, because they don&#x27;t have an expectation of privacy, it&#x27;s generally not legal to record audio without their knowledge.<p>It depends on states, but almost every state falls into the classification of one-party or all-party. In one-party states, at least one person being recorded must be aware of the recording. In all-party states, all parties being recorded must be informed.<p>These laws were originally written for telephone tapping, but my understanding is that they have been used in cases of bugging as well, even when no phone was involved.