The Systems Alliance is a supranational government that spearheads human space exploration and settlement in the Milky Way. The Alliance is responsible for the governance and defense of extra-solar colonies and stations, and officially represents humanity on the Citadel Council.
The Alliance was founded out of necessity, as no single nation could fund and manage the rapid expansion of humanity from Sol. The discovery of Prothean ruins on Mars had proven that alien contact was inevitable, earning international support for the Alliance that solidified after Alliance forces liberated Shanxi in the First Contact War.
Archived extranet articles, and Jien Garson's staff bulletins, reveal tensions between the Alliance and the Andromeda Initiative. Construction of dreadnought-sized ships and persistent rumors of AI development, which could have damaged humanity's standing on the Citadel, led to the Alliance demanding to oversee the Initiative's labs and shipyards. Negotiations continued until the day of the Initiative's departure.