The dative arguments with thematic roles of experiencer and possessor in the so-called dyadic unaccusative predicates, which are regarded as a quasi-transitive predicate with a vP phase here, trigger an intervention effect when the nominative objects move to the subject position above the dative argument, so inducing the unacceptable sentences. When a vP functions as a phase, the VP constituent will undergo transfer to the phonological and semantic components and thereafter cease to be accessible to further syntactic operations. At this point, the nominative object within the VP cannot move to the subject position. However, the dative argument does not trigger the intervention effect in the so-called typical unaccusative construction. Also in the passive construction, the complement can undergo movement to the subject position across the dative argument. At this point, the vP is not a phase because it is unaccusative by virtue of having no thematic external argument (e.g., no agent, no experiencer). When the syntactic derivation proceeds by merging the resulting vP with T, the VP-dative argument or nominative complement can undergo movement to Spec-TP for an EPP reason; hence, no intervention effect.