All images containing recognizable people require a model release. There are no exceptions. Look at the image and ask yourself “Could any of these people depicted recognize themselves in this picture?“ If so, you will need a model release. Sometimes the context of an image is enough to make a person recognizable, even if their face is not visible.
The most important things to remember are:
If the main subject of the image is a person – even if the person's face is not visible – it will require a model release. Images of people photographed from behind or without their permission or awareness will generally not be acceptable.
If the photograph is of a minor (a child under the age of 18), a model release must be signed by a parent or legal guardian.
A complete model release must be uploaded with each file that requires one. If you're uploading successive shots of the same model, the model release must be included with each image.
A model release must include the date the shoot took place.
A valid witness signature must appear on the model release. It must be from a third part – someone other than the photographer or the model/parent.
If the photo is of the photographer (a self portrait), a model release is still required. A model release for self portraits does not expire; you can have an unlimited date range on your self-portrait model release.
iStock does not accept digitally created or digitally signed model releases. This includes using script fonts as signatures, e-signatures, or scanning signatures and then pasting them into the release.