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The ACLU has a wealth of resources related to the rights of protestors. Clicking the below image will bring you to their website, where they answer many common questions concerning what is and is not legal during a protest.
Wondering about the Right to Peaceful Assembly? The Library of Congress provides an explanation:
Right to Peaceful Assembly: United States
This right is part of the First Amendment in the Bill of Rights. Take a look at it on the National Archives website: