. ▁Justice ▁Department ▁file d ▁suit ▁against ▁US G ▁and ▁six ▁other ▁wall board ▁manufact ur ers , ▁charg ing ▁them ▁with ▁price ▁fixing ▁under ▁§ § ▁ 1 ▁and ▁ 2 ▁of ▁the ▁Sh erman ▁Act . ▁The ▁claim ▁stem med ▁from ▁US ▁Gy psum ' s ▁ 1 9 2 9 ▁cross - lic ens ing ▁agre ements ▁for ▁its ▁pat ented ▁wall board , ▁which ▁set ▁prices ▁at ▁which ▁the ▁wall board ▁must ▁be ▁sold . ▁In ▁ 1 9 5 0 ▁the ▁Supreme ▁Court ▁forced ▁US ▁Gy psum ▁and ▁its ▁six ▁license es ▁ ▁who ▁produced ▁all ▁of ▁the ▁wall board ▁sold ▁east ▁of ▁the ▁Rock y ▁Mountains ▁ ▁to ▁ce ase ▁setting ▁prices , ▁and ▁US ▁Gy psum ▁was ▁enjo ined ▁from ▁exer cis ing ▁its ▁pat ent - lic ens ing ▁privile ge . ▁ ▁During ▁ 1 9 6 9 1 9 7 4 ▁in ▁the ▁United ▁States ▁District ▁Court ▁for ▁the ▁Northern ▁District ▁of ▁California , ▁a ▁series ▁of ▁civil ▁ant it rust ▁cases ▁were ▁heard ▁that ▁came ▁to ▁be ▁known ▁as ▁In ▁re ▁Gy psum ▁Ant it rust ▁C ases . ▁As ▁a ▁result , ▁US G ▁( t ogether ▁with ▁National ▁Gy psum ▁Company ▁and ▁Kaiser ▁Gy psum ▁Company ) ▁were ▁found ▁to ▁have ▁viol ated ▁§ ▁ 1 ▁of ▁the ▁Sh erman ▁Act ▁for ▁consp iring ▁to ▁establish ▁and ▁maintain ▁prices ▁of ▁gy psum ▁wall board . ▁ ▁In ▁December ▁ 2 0 1 2 , ▁US G ▁( t ogether ▁with