The Ninth Amendment is part of the Bill of Rights and provides further detail into the rights of United States citizens. The Ninth Amendment was developed primarily by James Madison.
James Madison focused on developing the Ninth Amendment to ensure that people did not believe the only rights that they had were those that were expressed in the Bill of Rights. There were arguments that this was unnecessary because there was no way that one could list out all of the rights that citizens had, and thus no one could provide an accurate document for rights. However, the Ninth Amendment was developed to specifically highlight that this was not the case.