There are currently 3 badge slots (each with 2 variants of the badge with 3 tiers each) which are not super clear as to how you earn them (I had to look it up online).

I rarely get any unless I'm purposefully targetting one (I earned the pacifist badge as it helped greatly in my attempt at unlocking the pacifist achievement, which makes sense) and feel that it could enhance the late game diplomatic gameplay as it could be used to indirectly (or directly) promote your standing for the Congress.