▁ 3 ▁January . ▁ ▁In ▁recent ▁years , ▁the ▁championship ▁has ▁varied ▁from ▁about ▁ 1 5 0 ▁to ▁ 4 0 0 ▁teams , ▁depending ▁on ▁the ▁capacity ▁of ▁the ▁host ▁institution . ▁With ▁jud ges ▁and ▁organis ers , ▁this ▁involves ▁ 5 0 0 ▁to ▁ 1 , 0 0 0 ▁participants ▁in ▁all . ▁ ▁The ▁competition ▁involves ▁nine ▁pre lim inary ▁r ounds , ▁which ▁become ▁" power - pa ired " ▁as ▁the ▁tournament ▁progress es , ▁matching ▁the ▁strong est - perform ing ▁teams ▁against ▁each ▁other . ▁Two ▁teams ▁form ▁the ▁" g overn ment " ▁(" pro position " ▁in ▁the ▁UK ▁and ▁North ▁America ) ▁and ▁two ▁the ▁" opp osition " ▁in ▁each ▁debate ▁room . ▁The ▁process ▁of ▁scoring ▁and ▁pair ing ▁these ▁teams ▁is ▁known ▁as ▁" tab bing ". ▁The ▁scoring ▁of ▁teams ▁is ▁done ▁by ▁jud ges , ▁most ▁of ▁whom ▁are ▁students ▁or ▁former ▁students ▁from ▁the ▁compet ing ▁institutions , ▁who ▁return ▁" ball ots " ▁with ▁their ▁scores ▁to ▁the ▁adj ud ic ation ▁team , ▁led ▁by ▁a ▁Chief ▁Ad jud icator ▁who ▁is ▁assist ed ▁by ▁one ▁or ▁more ▁deput ies . ▁The ▁deput ies ▁are ▁not ▁members ▁of ▁the ▁host ▁institution . ▁ ▁The ▁nine ▁pre lim inary ▁r ounds ▁are ▁followed ▁by ▁a ▁" break " ▁at ▁which ▁the ▁teams ▁proceed ing ▁to ▁elim ination ▁r ounds ▁are ▁announced . ▁This ▁is ▁tradition ally ▁done ▁on ▁New ▁Year ' s