On the basis of disjoint reference effect and control effects in Spanish and Korean finite clauses, I propose a Phase-based Binding Conditions, in which the local domain D is restated in terms of phase domain. It is argued that the volitional subjunctive in the obviation and control structures have defective T, since they are sharply dependent on the matrix T. For this purpose, this paper argues that the disjoint reference effect has a very narrow relation with the concordantia temporum between matrix and embedded tense. I assume that the CP with defective T is a weak phase CP, which cannot act as a phase for the binding interpretation. According to the Condition B, the null pronominal pro in obviation structure must be interpreted as disjoint from every c-commanding phrase in its phase, the matrix vP. The null anaphoric pro in control structure must be interpreted as coreferential with a c-commanding phrase in its phase, the matrix vP, as well, in compliance with the Condition A. In sum, this paper tries to account for the pronominal null subject in obviation structure in terms of Phase-based Binding Principles.