doesn't always shield a documentarian from a lawsuit, but it's a strong defense, and it may be required by your insurer, distributor, or exhibitor.
Releases. A release doesn't have to be in writing. Video releases -- in which the subject is video recorded agreeing to the terms of a release -- are also enforceable. A consent to participate may also be implied. In Clearance and Copyright: Everything You Need to Know for Film and Television, attorney Michael Donaldson writes how Lily Tomlin sued documentarian Nick Broomfield to stop distribution of his documentary about her one-person show. One of her grounds was that she and the people around her, never signed a release. The trial court ruled that neither Tomlin or the other participants ever objected to Broomfield's cameras, a failure that prevented later objection to their participation in the film.
Bottom line dept. If you can afford the attorney fees we would suggest consulting with an attorney knowledgeable about film clearance.