The founding document of the United Federation of Planets, signed in 2161, which sets out the principles member worlds must accept and is cited in several series as the measure of Federation values.
The Federation Charter is the agreement by which Earth, Vulcan, Andoria, Tellar and their partners created the United Federation of Planets in 2161. The Enterprise finale These Are the Voyages... is set around the ceremony at which Jonathan Archer is to speak before the signing.
The charter is treated as binding on any world that wishes to join. In the Deep Space Nine episode Accession, Sisko warns that a return to the D'jarra caste system would bar Bajor from membership, because the charter forbids discrimination based on caste.
It is also held up as an ideal. In the Voyager episode The Void, Janeway persuades the crews of trapped ships to pool their resources in an alliance she openly models on the charter's principles of co-operation.