To be perfectly honest I'm not 100% sure whether this should go back in the Presidential thread since technically by overriding the veto this has already become law. Did we ever have a successful veto override in-game?
Yes, but…there is another point here. In Atlasia, the 2/3 margin is generally marked to be 2/3 of all Senators, not 2/3 of those voting.
In the actual US constitution the first time 2/3 is mentioned it is specified that it means 2/3 of those present, and every subsequent invocation is understood to mean the same. The Atlasian constitution never makes reference to two thirds of those present and simply states two thirds (except for constitutional amendments, which explicitly say “two thirds of membership”). I’m not sure I ever remember any 2/3 vote being declared without actually having 2/3 of the whole Senate.