Credibility assessments in asylum visa applications have attracted criticism across diverse research fields. This article builds on existing critical examinations by presenting a case study of a successful appeal in the Federal Court of Australia (FCA) which overturned a decision involving one such problematic credibility assessment. The article establishes that credibility assessments often rely on flawed language ideologies and reasoning that transform the asylum seeker into the sole participant responsible for the texts produced in institutional processes. As a contrast, it then explores the FCA decision, analysing the judge’s treatment of three different premises on which the lower-level rejection relied. It demonstrates how, when dealing with each of these premises, the judge’s approach aligns with sociolinguistic scholarship. The case study demonstrates the potential of sociolinguistic awareness to denaturalize the problematic ideologies underlying credibility assessments. However, the article equally acknowledges and discusses the systemic limitations on challenging credibility assessments, due to the narrow scope for judicial review, and the need for professional legal assistance to argue one’s case successfully. The article concludes that while credibility assessments serve to act as a powerful gatekeeping tool to support increasingly restrictive asylum policy, judicial receptiveness of sociolinguistic understandings of communication can sometimes provide an avenue for successful appeals. It thus provides a powerful example of the potential benefits of communicating sociolinguistic research to law students, legal practitioners and decision-makers.