Model Property Release Info
Written releases are not required, as being unnecessary, in many circumstances. For instance, releases may not be needed for crowd scenes containing many (anonymous) people or where the photographs are being taken in a context where implied releases which are sufficiently broad are clearly given. And in general, public places don't require a property release.
In other cases releases are highly recommended. In case of doubt, e.g., a distinctive profile or silhouette which can be identified by a person knowing that person, get a release. You may wish to educate yourself more about the advisability of obtaining releases and the different wordings for releases by reading books for photographers.
As a general guideline you should definitely get releases from any person (or their parent or guardian where a minor is involved) who can be identified in a photograph. Also, photographing trademarks and works in which there is copyright is problematic. Stock photographers usually try for contemporary art-free and logo-free photos to eliminate problems.
As stated above, in case of doubt get the releases, or, check questions about particular circumstances with a lawyer. The facts of the specific case decide whether a release is necessary.
For an example of a model agreement, see Model Agreement.
Note : This agreement can also be found through the sign up process for a pro-membership by clicking on 'Pro Terms' next to the terms and agreement section.