Climate citizens’ assemblies convene randomly selected citizens who, after structured learning and deliberation, develop policy recommendations. Whether they produce more ambitious recommendations and influence political decisions remains contested. This research conduct a comparative, counterfactual assessment of 488 recommendations from five national and one state-level assembly in Western Europe, drawing on document analysis and expert interviews. The results show that citizens consistently proposed more ambitious climate measures than existing government policy. Recommendations sometimes influenced policy by adding momentum, enriching plans, breaking deadlocks, or introducing novel ideas, but such influence was rare.

Citizens were more ambitious than governments

The study found that all climate assembly recommendations were either more ambitious than current government policy or neither more nor less ambitious. This finding was consistent across all six cases, including Austria, France, Germany, the UK, Scotland, and Berlin. Out of 488 recommendations in total, 327 (67%) were more ambitious, and 133 (27%) were neither less nor more. No recommendation was clearly weaker than current policy. For 28 (6%) recommendations, the data were insufficient to make an assessment.

Recommendations in the ‘more ambitious’ category demanded that governments or parliaments act beyond existing policies, for instance, by enacting new policies or tightening the coverage of existing ones. These ranged from stringent regulatory interventions, such as banning domestic air travel in France, to ambitious policy targets, such as retrofitting all homes by 2030 in Austria, to softer measures like raising public awareness about localized living in Scotland. Recommendations in the ‘neither’ category were similar in ambition to existing policy, with differences being vague, minor, or reflecting only a repackaging of what already existed.

Some citizen recommendations altered policy decisions

The researchers found evidence of causal impact, though with strong variation between cases. In half of the assemblies—Germany, Scotland, and the UK—none of the recommendations causally translated into political decisions. In Austria and Berlin, only 1 (1%) and 2 (4%) recommendations, respectively, resulted in decisional changes that would not have occurred without the assembly. In France, by contrast, 48 (33%) recommendations showed this kind of decision-making impact.

For recommendations with impact, the study identified several causal mechanisms. Most frequently, recommendations added substantial elements to existing or planned initiatives (‘enriching impact’) or reinforced momentum behind them (‘fortifying impact’), with both mechanisms occurring 29 times each. In eight cases, recommendations introduced novel ideas not previously debated by policymakers (‘innovating impact’), and in seven cases, they helped break political deadlock (‘political impact’). No evidence was found that recommendations stopped policy plans (‘inhibiting impact’) or fundamentally changed government positions (‘shifting impact’).

Why some assemblies have impact and others do not

The analysis suggests that what sets the French case apart was the interplay of unusually high levels of political leadership and power delegated to the assembly, resulting in public pressure. In France, the President granted the assembly a ‘co-governance’ role, expecting it to produce legislative proposals for Parliament or a referendum ‘without filter’. This ‘quasi-legislative mandate’ gave the assembly unparalleled political weight and drew exceptional media attention.

In other cases, political leadership was limited or fragmented. The German assembly lacked policy impact largely because it was a civil-society initiative without institutional anchoring. The UK assembly was a parliamentary process with limited government engagement intended to help Parliament hold the government accountable. In Austria, the assembly quickly came to be seen as a partisan ‘Green-Party project’, while the Scottish assembly was seen by some government actors as externally imposed by Parliament.

Why some recommendations have impact and others do not

Even in France, only one in three recommendations impacted decisions. The most frequent explanation for a lack of impact or dilution was opposition from interest groups, ministries, and parliamentarians. Other barriers included incompatibility with constitutional or European Union frameworks and the vagueness of certain recommendations. Political opposition was often attributed to ‘false good ideas’—shared goals but disagreement on means—as well as perceived radicalism or unfeasibility.

Discussion

The analysis confirms that assemblies can prioritise policies typically shunned by elected politicians, acting as a remedy to electoral and partisan constraints. However, under the current ad hoc advisory model, decision-making impact depends on unusually favourable political conditions. Often, governments engaged in ‘window-dressing’—signalling responsiveness without substantive change—or diluted recommendations. The study suggests that even sophisticated assembly design is insufficient for policy impact if the political context is not supportive.