Conventional is a synonym of Normal. Normal is the opposite of Weird. Weird is etymologically related to Worth. 
Law is related to Government. you are likely to find Government in/at/on Country. Country is related to People. 
Conventional <--Synonym--> Normal <--Antonym--> Weird --EtymologicallyRelatedTo--> Worth 
Law <--RelatedTo--> Government --AtLocation--> Country <--RelatedTo--> People 