Intermediaries are crucial in bridging the communication gap between vulnerable individuals and the complexities of the criminal justice process. They advise legal professionals on effective communication and how to adapt questioning techniques and advocate for necessary adjustments to ensure meaningful participation and uphold fundamental human rights. While most Australian jurisdictions have adopted an intermediary scheme, variations in legislative scope, policy and practice exist. This article analyses these diverse schemes through a human rights lens, drawing upon research and existing evaluations of intermediary schemes to highlight the positive impact of intermediaries on communication and evidence quality. Inconsistencies across the jurisdictions regarding eligibility criteria, procedural accommodations and access raise concerns about equitable access to justice and compliance with international and domestic human rights obligations. Given this fragmented landscape, the article examines the effectiveness of these intermediary schemes across all vulnerable participants—including children and adults with cognitive or communication disabilities—and advocates for a nationally harmonised framework. Such a framework would ensure consistent standards, training and access, in turn, promoting fairness, efficiency and alignment with international best practices, as well as enhancing procedural justice for vulnerable adults. Moreover, the article submits that a national scheme would yield economic benefits, justifying government investment.