This chapter aims to advance the discussion on how to implement sustainability objectives in existing investment treaties through treaty interpretation. Moving away from the focus on the interpretation of the concept of sustainable development or the term ‘right to regulate’ written into an investment treaty, this chapter argues that what is elementary to treaty interpretation is whether the interpretation process and final decision are approached in a balanced and inclusive way. This argument is based on the premise that sustainable development is a balanced concept, which encompasses social, economic and environmental concerns. Analysing the implementation of sustainable development objectives in international investment law through the lens of treaty interpretation, this chapter examines two distinct interpretative approaches. One is the balanced concept adopted by arbitrators, which conceives of sustainability as an inclusive, comprehensive consideration of all relevant concerns in decision making. The other is a creative revision of the reasonable person and government test. The reasonable person test paves the way to shape good governance and business practices in light of sustainability objectives in international investment law. This chapter suggests that sustainable objectives can provide a new benchmark to define the viewpoints and decisions of a reasonable investor or government.