The NHA is a trade and military conglomerate ruling over much of the Red Rift cluster which before and after the arrival of the humans was a center for consumer product manufacturing, and is civilized by comparison to much of the Rift. It's composed of 6 garden world colonies and several dozen minor stations and habitats.
The NHA was founded shortly after the humans settled New Havana in large numbers during the colony rush after the First Contact War in 2168 CE. In an effort to be seen as no threat, they declared New Havana a free trade area and neutral ground for the factions within the Red Rift. The NHA was founded 5 years later over a mutual desire for peace and trade between the strongest colonies. The new-formed body was named after the planet where the final contract was signed by its founding members. Not much later most of the minor factions joined up too.
While the NHA is multi-species it is overwhelmingly dominated by turians, asari and humans with a notable salarian and batarian minority. Their economy is focused around producing consumer goods for other Terminus systems and factions, taking advantage of the steep cost that is associated with cargo from C-Space. C-Space corporations relocated to the NHA, but had to face the fact that the NHA regulation - while not as strict as in C-Space - was only slightly better. However, the location of the Red Rift cluster, on the far side from Illium, made it a popular choice for businesses that seek a compromise between the creature comforts of C-Space and the lax/nonexistent Terminus regulations. The steady influx of corporate money has sparked a boom that is still lasting and galvanized the former colonies to view themselves as proud members of the NHA, seeing in it more that a coalition of necessity.
The political system is varied and differs from member to member, but all have to adhere to the NHA Senate and Council who act as lower and upper chamber respectively, and have to enforce laws and regulation in the NHA treaty. The Senate is formed by mass voting, giving seats to parties relative to the turnout. As a result, parties with similar programs have entered alliances to become a player on the senate since most parties only have outlets on a minority of member states. The senate makes laws about economic regulations, declares war and peace and votes over the budget and matters of interstellar diplomacy. Amendments to the treaty itself need 2/3 of the Senate and 2/3 of the Council to vote 'yay' for it.
The Council is made up of representatives from the ruling government in the respective member states and is balanced by population size. Any regulations and laws that will affect member states on a state (or lower level) will have to pass the Council after the senate voted in favor of it.
The executive organ is headed by the High Minister who is rotated every 2 years and is always from a founding state. His subordinate ministers need approval by the Senate. In judicial matters, the High Court is the last instance that rules in matters of interstellar conflict within the NHA and about due process within the NHA bodies. It does not take cases that are an internal matter of the member states.
The military of the NHA, the New Havana Defense Force (NHDF) was originally composed of its member states' current militias but has in recent years received "homegrown" additions and seeks to unify its command and infrastructure to accommodate its role as protector and supreme enforcer of the NHA cluster-wide. The adoption of the first five Triarius Class heavy cruisers was seen as the ultimate symbol that the formerly separate entities have become an interstellar power to be reckoned with.
Calling NHA as a pint-sized C-Space wannabe is close to the truth, but tends to gloss over the fact that slavery isn't abolished and is practiced in 2/3 of its member states. However NHA rules have turned it into an unofficial indentured servitude scheme similar to that on Illium. About 1/4 of its members are ruled by dictators or a similar ruling class in a few cases mirroring medieval dynasties and its population are only allowed to vote for the Senate; freedom of press or opinion is not guaranteed by the NHA. The NHA does not interfere with internal lawmaking and conflicts that are not a full-blown civil war and if it is, the NHA makes a point in siding with the last legitimate government however unjust it was, when sending its fleets to aid. If there isn't an NHA ruling or law about it the member states are free to make laws within their respective sovereign territory.
The Reaper War
The war started slow for the Red Rift, warbands from puppet nations and increasing refugee streas put a strain on the NHA's resources but the could handle that.
Things took a turn for the worse when the first Reaper fleet arrived and cleaved through the NHDF navy with little effort. It wasn't until the Geth fleets arrived to give the NHDF a much needed respite, but when the geth traveled on to C-Space, the reapers came back. New Havana was the first to fall, followed by Lartus. The NHDF was forced to hit-and-run tactics based from hastily improvised and uncharted supply depots to stall the inevitable.
It wasn't until the last month of the war that the NHA government ordered the navy to abandon the cluster, in response to loosing the last remaining supply depot. The navy was sent to reinforce anti-Reaper forces elsewhere.
When the crucible fired and months later the remaining fleet returned, the Red Rift was a burned-out husk of itself.
Many smaller nations were disfunctional, and the larger ones were struggling with simply keeping the population from starving since the Red Rift had been a net-importer of foodstuffs in the past.
It was decided to enter a phase of colonization of garden worlds that hadn't yet been exploited, and to set up agricultural and mining operations to alleviate economic and social woes of the core worlds. Still, the efforts are running on a shoe-string budget and it is anticipated that many of these colonies will depend on their own resources to supply themselves from the beginning.
As a secondary measure, a large convoy made up of large freighters and any military vessel that could be spared was sent into the uncharted space to find a viable route to Omega. This route, dubbed the Silk Road, will serve as a lifeline to the greater galactic community. The travel is dangerous and gas planets for discharge are few. The NHDF has set up outposts and gas mining operations to ensure that every ship can be supplied that take the Silk Raod, but those are often target of pirate raids themselves.