What Drives Forum Rule Adaptation: Investigating the Influence of the Forum Founder and Polycentric Governance Linkages in Dutch Strategic Spatial Planning

ABSTRACT Forums play an important role in addressing interdependent policy issues, and their effectiveness depends on the continuous adaptation of forum rules. Yet, it remains unclear whether rules are exclusively used and adapted to improve forum effectiveness. In this article, we therefore investigate the influence of individual goals of forum founders, forum interdependencies, and changes in higher‐level institutions on the use and adaptation of forum rules. To this end, we conduct a case study of a state‐initiated geographically transboundary forum in Dutch strategic spatial planning. Building on in‐depth interviews, document analysis, and nonparticipant observations, we find that forum rule adaptation is driven by a combination of finding effective policy solutions, the individual pursuit of the forum founder to create a new national spatial vision, the formation of the national government, provincial elections, the fall of the national government, and decision‐making in other forums. These findings suggest that forum rule use and adaptation results from an interplay between seeking forum effectiveness, the self‐interest of forum founders, and various polycentric governance linkages, rather than the desire to improve forum effectiveness alone.