Today's Stellaris dev diary is about The Galactic Community, which will be a part of Federations.
Resolutions are proposals you can put to the Galactic Community (GC) that add passive modifiers (positive and negative) to all empires and may have conditions you must satisfy to avoid being in breach of Galactic Law.
So anyone can propose Resolutions to the GC, and only one proposal can be considered at a time: others will be put in the proposal queue. When a Resolution is either passed or rejected, the next Resolution proposal in the queue is put forward. However, the queue is ordered according to Diplomatic Weight, so empires with high Diplomatic Weight will have higher priority given to their proposals. Diplomatic Weight is calculated based on tech level, number of pops, fleet strength and economy. It looks like the GC Senate goes into recess (don't know how often) so this might prevent prevent proposals being spammed. I don't know if there's a cost to proposing Resolutions but I assume there has to be a way to prevent the big diplomatic powers from completely smothering all other debate.
When empires vote on proposals, their Diplomatic Weight is added to either Support or Oppose (you can also Abstain). The total weights are compared and decide whether or not it is passed. Empires can call in Favours from other empires, which adds 10% of their Diplomatic Weight to a proposal for each Favour you call in. You can only be owed 10 Favours per empire, and are also used to improve your chances of securing a diplomatic deal with that empire. Favours can also be traded.
You can reform the GC to have a Galactic Council, comprised of the 3 empires with the highest diplomatic weight (though this number can be changed through Resolutions). Council members get powerful abilities to exercise over the rest of the GC, such as vetos and emergency votes (which bypass recess).
You can set a Galactic Focus (probably through a Resolution), which guides the GC towards a common goal like combating a crisis (which will make it illegal to close your borders to other GC members during the crisis). The Galactic Market is now founded as a Galactic Focus, and the GC itself is founded when one empire meets half the others. You can apply to join the GC if you know a member state, and you can also choose to leave it if it's screwing you over.