I concur with the above. My question was about diplomacy and organized means of inter-species or -government conflict resolutions.

As a hypothetical:
In the Red year 5207, the destruction of a Red colony occurred when Mantis mining operations destroyed the biosphere of Paradise Colony.

In an act of revenge, the Red colonists armed themselves and destroyed the mine, then went on to attack other Mantis colonies.

Both sides were gearing up for war when envoys from both sides petitioned the Giants to withdraw support from the other side. The Giants arbitrated a peace deal which included the 'Right of Occupancy' which grants title to a world to the beings who occupy it, and by establishing a Board of Arbitration to resolve disputes.

Since it's inception, all of the major races have at least some governments as signatories, except for the enigmatic Caterpillars. The facts that many governments have not signed on and that there is no provision for enforcement are often cited as reasons for continued hostilities on the frontiers.