Urban land use planning and policy decisions are often contested, with the multiple stakeholders (business, developers, residents, policymakers and the wider community) frequently holding opposing viewpoints about the issues and best solution. In recent years, however, the participatory process of social impact assessment (SIA) has received significant attention as a way to mitigate conflict, facilitating negotiation and conflict resolution. This paper examines how social impacts have informed development appeals in Australia, focussing on ten cases from the Queensland Planning and Environment Court (QPEC). Half are appeals from community members (typically neighbours) wanting to oppose approvals and half from organisations appealing against City Councils decisions to deny their development applications. While legal challenges do not necessarily reflect attitudes and practices, they provide a means to begin to assess how social impacts (although not often explicitly defined as such) inform development related disputes. Based on the nature and outcomes of 10 QPEC cases, we argue that many legal cases could have been avoided if SIA had been undertaken appropriately. First, the issues in each case are clearly social, incorporating impacts on amenity, the character of an area, the needs of different social groups, perceptions of risk and a range of other social issues. Second, the outcomes and recommendations from each case, such as negotiating agreements, modifying plans and accommodating community concerns would have been equally served thorough SIA. Our argument is that engagement at an early stage, utilising SIA, could have likely achieved the same result in a less adversarial and much less expensive and time-consuming environment than a legal case.