I thought I would share this article, it states if you are on public property, or YOUR property, L.E.O. are NOT in legal standing to turn your recording devices off ( unless you are obstructing justice )
The one thing I would caution on is YMMV depending on the state you are in. Different states have different laws regarding recording. For example, in MA the MA Supreme court ruled it is legal to record the police as long as you are not trying to conceal the recording.