Abstract: From a typological perspective, the morphological coding of case marking varies due to different syntactic functions of the noun phrases to which case markers are attached, with either overt or covert marking.There are different alignments among the single argument of an intransitive predicate (S), the agent argument of a transitive verb (A) and the patient argument of a two-place transitive verb (P) in the morphological coding of case marking, thereby creating a tetrachoric table of language patterns.The present study finds one implicational universal concerning language patterns: given the non-cooccurrence of the case marking of A and P as well as the same marking of S with A or P, if S is coded in overt form, S tends to have the same case marking with A.This universal results from the interaction of iconicity and economy of language.The study provides some logical support for the Hierarchy of Grammatical Relations, and a new perspective on the standards of subject in a typological sense, especially on those of the ergative languages.