I'm thinking of a few different senerios:
1. Encounters with police on your own property. Either video or audio or both. With or without the officers knowledge.
2. As above but on public property.
I am not thinking about telephone conversations.
Thanks for taking the time to answer my question.
Some of the most egregious acts of police force were exposed by someone watching (recording!) but as said below, don't get too close or you'll hope someon else is taping you.