Beyond Mandatory Participation: A Classification of Non-Statutory Participatory Methods

Public participation is integral to contemporary planning and decision-making, yet knowledge of methods beyond formally prescribed procedures remains fragmented across the academic and practice-oriented literature. Terminological inconsistencies and overlapping concepts further complicate their identification and practical selection. This study develops a systematic framework for identifying, classifying, and characterising non-statutory participatory methods and examines their relevance across spatial planning phases. An exploratory, scoping-oriented literature review, combined with qualitative content analysis and conceptual synthesis, examined 96 publications containing identifiable participatory methods. The initial 869 entries were conceptually consolidated by distinguishing methods from aliases, variants, methodologies, and umbrella categories, resulting in 124 participatory methods, 76 aliases, 128 variants, and 12 methodologies. Based on their primary purpose, methods were organised into ten functional categories, while secondary functions captured their cross-functional applicability. Method characteristics and broader participatory approaches were additionally distinguished, and functional categories were mapped against seven spatial planning phases. The findings demonstrate that participatory methods are neither conceptually discrete nor restricted to a single function, but may extend across functional categories and planning phases. The framework makes the functional diversity and relationships among non-statutory participatory methods more explicit, providing a structured basis for their initial identification and comparison according to participatory purposes and potential relevance to different planning phases, rather than a comprehensive tool for context-specific method selection.