The Collaborative International Dictionary of English v.0.48:
Gag law \Gag law\ (Parliamentary Law) A law or ruling prohibiting proper or free debate, as in closure. [Colloq. or Cant] [Webster 1913 Suppl.]WordNet (r) 3.0 (2006):
gag law n 1: a rule for limiting or ending debate in a deliberative body [syn: closure, cloture, gag rule, gag law] 2: any law that limits freedom of the press