Null subjects in indicative clauses in Brazilian Portuguese display all the diagnostics of obligatorily controlled PRO. Based on Hornstein (2001), Ferreira (2000, 2004) and Rodrigues (2002, 2004) analyze those instances of null subject as traces (deleted copies) of A-movement, i. e. finite control structures. In this paper we show that there are two types of subjunctive clauses in this language: one that does and one that doesn't allow finite control. I further show that non-obligatory control subjunctive complements always trigger obviation (Disjoint Reference Effect) (Picallo 1985; Raposo 1985 among others). This paper gives a unified account for subjunctive obviation and the lack of finite obligatory control in some subjunctive complements in Brazilian Portuguese. Building on Hornstein’s (2007) approach to Principle B, the proposal put forth here reduces both facts to reflexes of one and the same syntactic property: tense defectiveness.