House Gag Rule is a decision to 
USA in the chain of events and decisions in the American Civil War.
It requires that USA has an average consciousness of 3.0, and it lowers the consciousness by 2.0 for all POPs in the states.
The in-game text says: The seemingly irresolable debate over slavery threatens to tear our country apart. If we were to introduce a gag rule in the House of Representatives, barring bills on the slavery issue from being presented to the House, we could hope to at least alleviate some of the worst tensions.