Is Audio Surveillance Legal? Depends on Your State
If you're considering adding an audio component to your video surveillance system, you'll want to carefully research the audio surveillance laws in your state to avoid potential lawsuits and/or criminal charges. Recording conversations can be a violation of privacy, so it's crucial to not only research -- but also understand your state's laws.
Let's take a look at Oregon's laws, where VideoSurveillance.com is located. In Oregon, all parties (or persons) must be informed of and consent to being recorded in a private conversation before a recording can take place. However, conversations occurring in the public sphere, i.e. in a park or walking on the street can technically be picked up on video without the need for consent because of the limited expectation of privacy in these places.
For a summary of each state's audio recording laws, see the following guide: http://www.rcfp.org/rcfp/orders/docs/RECORDING.pdf
Be sure to also speak with an attorney in your state about any lingering questions you have concerning audio recording. States where audio surveillance is permitted often require signs informing all parties that their conversations are being recorded. Here's an example of an audio recording notice: