term:

Gag Rule

gag rule n

: a law, order, or ruling that prohibits free debate or expression of ideas, information, or opinions [a long-standing Florida gag rule barring people from discussing complaints they made against police officers "National Law Journal"]
;specif
: a rule limiting or prohibiting debate on an issue in a legislative assembly (as the U.S. House of Representatives)

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.