In the late 1990s a group of Victorian local government councils addressed a sustainability void in the building codes and planning regulations by developing capacity to implement Ecologically Sustainable Development (ESD) via the planning system. What began as a collection of largely independent initiatives progressed to an integrated suite of mechanisms to embed ESD in development assessment at the local level. In the absence of leadership at both the national and state levels, the now officially formed Council Alliance for a Sustainable Built Environment (CASBE) is continuing to advocate for and enable local governments to upscale and embed ESD policies and decision making processes. In this paper we examine the efforts of CASBE councils to achieve ESD outcomes through planning over this 15 year period, and the response of the development sector and State government. To do this we examine Victorian Civil and Administrative Tribunal decisions over recent decades that address cases where ESD initiatives are a requirement of permit condition. These cases reveal the contested dimensions of achieving ESD via the development assessment process. We find a variety of justifications mobilized over the study period to both remove and retain ESD conditions, with interventions to remove outnumbering those to retain. We find several inconsistencies in how these reasons are substantiated and mobilised over time, resulting in an ongoing lack of clarity regarding the States’ position on the role that planning policy and development assessment should take in achieving ESD outcomes.