Constitution of the United Federation of Planets

From Memory Alpha, the free Star Trek reference

A "constitution" typically is a document which states the fundamental political principles of a governing body. The Constitution of the United Federation of Planets is such a document and contains at least twelve "Guarantees" related to fundamental individual rights of citizens. The Seventh Guarantee against self-incrimination during legal proceedings was considered by Captain Picard in 2367 as "one of the most important rights granted by the Federation." (TNG: "The Drumhead") In some instances those protections related to fundamental rights can be extended to non-citizens while on Federation territory (such as a Starfleet vessel). (TNG: "The Perfect Mate")

The relationship between the UFP Constitution and the Federation Charter is unclear. Both contain rights for individuals; as Sisko put it in DS9: "Accession": "caste-based discrimination goes against the Federation Charter". It is most likely that the Charter describes the requirements for entry of a planet into the Federation (e.g., no entry if caste-based discrimination is in place), while the Constitution describes the principles, governing structure, and citizen rights once becoming a member (e.g., rights against self-incrimination).