Evidence-based policymaking and spatial planning. Factors of evidence utilisation

This paper investigates the role and usability of expert-generated evidence in democratic policymaking, with spatial planning as a case study. Drawing on the literature on evidence-based policymaking in political science and planning, and employing the CRELE and ACTA frameworks with a critical realist approach, the study analyses the attributes that enhance evidence consideration by decision-makers and their interplay with political rationales. The research is based on a survey of municipal policy-makers and interviews with regional legislators and stakeholders in Lombardy, Italy. The findings indicate that comprehensiveness and relevance are key determinants of evidence usability, alongside source credibility and the perceived legitimacy of the planning process. However, while timeliness proves significant in spatial policy rulemaking, its impact is less pronounced in local planning itself. Crucially, policy preferences, including electoral commitments and responsiveness to stakeholder interests, consistently influence how decision-makers evaluate evidence. Instead of viewing evidence, political reasoning, and interest-driven motivations as separate and competing forces, decision-makers integrate them in a pragmatic manner. Our analysis details the descriptive validity of the CRELE and ACTA frameworks in spatial planning, adding evidence for their strengthening. In particular, credibility and legitimacy emerge as interconnected rather than distinct dimensions, while electoral accountability appears as an independent driver influencing evidence utilisation. These results confirm that frameworks gauging evidence usability should not overlook the political and contextual contingencies that shape decision-making. Future research should further investigate the balance between generalisable models and local variables that determine how evidence informs policy.