gag rule

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A rule, as in a legislative body, limiting discussion or debate on a bill or resolution under consideration.
• noun A rule or policy preventing the discussion of certain issues by private parties as a condition of the receipt of public funding.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a rule for limiting or ending debate in a deliberative body