Does citizen deliberation inside representative institutions enhance legitimacy among non-participating publics?

Claims that citizen deliberation can strengthen public confidence in democracy rest on the assumption that it enhances the perceived procedural legitimacy of democratic governance. We test this assumption by examining whether integrating deliberative constituent forums into electoral-representative institutions increases perceived legitimacy among non-participating publics and which specific features of such forums drive these diffuse effects. We extend existing experimental research on democratic innovations by theorising that the deliberative norms of consequentiality and listening shape legitimacy judgements. Drawing on a nationally representative survey vignette experiment in Australia, we show that even minimal, realistic exposure to information about a deliberative citizens’ panel informing a parliamentary committee produces a modest but statistically significant increase in perceived procedural legitimacy. These gains depend on signals that citizens’ input is taken seriously and that participants are sincerely listened to. While legitimacy declines when deliberative input is ignored, the strongest positive effects arise when processes visibly communicate high-quality listening by political representatives. Moreover, legitimacy gains are strongest among respondents with low institutional trust. The findings demonstrate that the legitimacy-enhancing potential of deliberative innovations hinges not only on institutional design but also on the perceived relational quality of engagement between constituents and decision-makers. This contributes to ongoing debates in democratic theory and political behaviour about when and why deliberative innovations can rejuvenate representative democracy.