The Coalition of Planets was founded in August 2155. It was an alliance between eight species of the Alpha and the Beta Quadrant. The Coalition is generally seen as a precursor to the United Federation of Planets, even though the coalition was an interstellar cooperation alliance as opposed to the United Federation of Planets being a suprastellar territorial union with a common code of constitution.
Members of the Coalition of Planets included Earth, Vulcan, Tellar, Andoria, Coridan, Rigel, Denobula, Draylax, Trill, Delta and Risa.
The Coalition of Planets was a political “melting pot” for bilateral treaties between the member worlds with a special focus on economy. The Babel Accords, signed on the famous planetoid of the same name, laid down the foundations of the Coalition.
Besides a unilateral pact of non-aggression and recognition of all territorial borders, members of the Coalition of Planets would establish a common currency exchange program and a free trade zone. They also guaranteed support and save spaceports to all member vessels of the Coalition.
While the Babel Accords explicitly forbade alliances with enemies of Coalition members, there was no common defense statement included due to the veto of the pacifist movement of the Vulcans and the Riseans. However, the Accords encouraged members to form bilateral defense treaties and it became common understanding shortly after the foundation that a species that attacked one member world would have to deal with the whole Coalition.
Every year, one of the member worlds would take the chair and host the annual conferences of the Coalition. While it may seem flattering that the chosen official language was terrestrial English, the simple fact was that with English being by far the easiest and one-dimensional language this was a logical choice. Besides that, Humans and Vulcans continued to be the driving force of this alliance and invested far more resources into the project than the other member worlds.
The sovereignty of the respective member worlds remained unaffected even though many aspects of interstellar cooperation deeply influenced everyday life everywhere: The Coalition medical Exchange Program and the Coalition education cooperation were two programs that quickly helped to raise living-standards on all member worlds. The Human Diplomatic Corps helped to establish embassies of all Coalition worlds and a new understanding of interstellar jurisdiction emerged from the installation of Coalition arbitrators that were bound to solve legal problems between different species within the Coalition.
While the Coalition of Planets had only about one year before the Earth-Romulan War, the alliance continued to grow stronger during war-time and eventually led to the founding of the United Federation of Planets in 2161. However, the Coalition was not dissolved after that but continued to be an economical alliance for more than 100 years until 2270. Many species that wanted to join the Federation would apply for a Coalition membership first and it was later considered to be mandatory to have been a CoP member before getting a seat on the Federation Council. Coridan, for example, did not join the Federation until 2168. The intense mining operations conducted on the home planet of the Coridans led to massive ecological pollution and a subsequent exodus of over 60 percent of the population to other planets and colonies. The remaining Coridan organizations were quickly absorbed by Orion enterprises with questionable backgrounds. That was why the Coridans were forced to leave the CoP in 2201 when they refused to expel Orion officials from their installations after a Tellarite outpost had been destroyed during an Orion raid.
Another example would be Risa that also was a founding member of the CoP but did not want to commit to a suprastellar organization including defense as this not only violated the Risean constitution but also was against the neutrality-principle most Riseans adhered to. Risa only became a fully-fledged member of the United Federation of Planets in 2349 during the Federation-Cardassian War when the Cardassian offensive came dangerously close to Risa.