You need to get a model release when there is a person in the photograph. When in doubt get a model release, otherwise your entire shoot runs the risk of not being accepted.
Even when people are not recognizable, they should sign a model release.
A tattoo is considered and identifying feature, and always requires a model release.
What’s a model release and why is it required? A model release is a written permission from an individual, allowing the use of their likeness for commercial purposes (to sell, promote, or endorse a product). Releases protect you, and the customers who license your content for their projects, against the future possibility of a claim from people depicted in your content.
Is a model release always needed? A model release is required for each recognizable person, regardless of whether they are the main subject of your shoot or in the background. Keep in mind that a person may be recognizable by the clothes they wear, or the people they’re with.
Model releases for people in large crowds are only needed if a person or a few people are the focus of a shot or can be digitally isolated.
Please always remember to give your image and model release files corresponding filenames.