Democratic legitimacy and multi-stakeholder platform design in sustainability governance

Addressing complex sustainability challenges such as food system transformation requires cooperation across sectors, governance levels, and stakeholder groups. Yet such cooperation is often hindered by conflicting interests, distributional tensions, and declining trust in political institutions, which challenge both the input and output legitimacy of representative democratic decision-making processes. Deliberative and participatory sustainability governance mechanisms often struggle to deliver effective policy outcomes with high output legitimacy, while technocratic forms of sustainability governance often lack democratic input legitimacy. We argue that well-designed multi-stakeholder platforms (MSPs) can generate synergies between input and output legitimacy, rather than reinforcing trade-offs, thus serving as meaningful complements to representative democratic institutions. Drawing on sustainability governance and democratic legitimacy literatures, we develop a framework linking key MSP design features to both forms of legitimacy. We illustrate this through Germany's Commission on the Future of Agriculture, an MSP, and conclude with a research agenda on MSP legitimacy in sustainability governance.