Laws and regulations can quickly become outdated or can have unintended consequences that undermine policy objectives. Regular evaluation of rules after they have been implemented (ex post) helps policy makers to understand how they work in practice and what changes might be needed to improve and adapt them. Evaluation is also vital for removing unnecessary regulatory burdens on businesses and citizens and making rules easier to comply with. Making evaluations and follow-up actions publicly available can increase government accountability and responsiveness.
The OECD Indicators of Regulatory Policy and Governance (iREG) survey measures the quality of ex post evaluations for both primary laws and subordinate regulations in OECD countries and found significant scope to improve ex post evaluation in both areas. On a scale from 0 to 4, the average score across OECD countries for ex post evaluation of primary laws in 2024 was only 1.34. Only 9 out of the 38 countries with data available, and the EU, achieved a score of 2 or more. There are significant deficiencies in all four aspects of ex post evaluation: methodology (with an OECD average score of 0.36 out of 1 in 2024), systematic adoption (0.36), transparency (0.37), and oversight and quality control (0.25). The average score for ex post evaluation of subordinate regulations was similarly low, at only 1.33. Again, only 9 out of the 38 countries, plus the EU, achieved a score of 2 out of 4 or better. The scores for ex post evaluation are very similar in most countries for both primary laws and subordinate regulations (Figure 8.7).
Moreover, there has been only limited improvement since 2014, when the OECD average score for ex post evaluations of primary laws was 0.89 (Figure 8.7). OECD countries have seen an average increase of around 0.12 points each in the three dimensions of oversight and quality control, methodology, and transparency. Systematic adoption has seen a smaller improvement (+0.06 points), as countries have not expanded their formal requirements for evaluations (OECD, 2025).
Governments could improve their systematic adoption of ex post evaluation by ensuring that it systematically covers all regulations, or at least targets those that have the greatest impact to ensure the best use of evaluation resources. Currently ex post evaluations remain largely ad hoc. Only 7 of 38 OECD countries (18%) require periodic ex post evaluations of all primary laws, and a further 4 countries (11%) for all major laws. 13 countries (34%) require them for only some primary laws, and the remaining 14 (37%) have no requirements at all (Figure 8.8). The lack of a systematic approach creates a risk that evaluations may instead be chosen based on politically driven priorities or in response to regulatory failures.
Governments can also improve their ex post evaluation methodologies by providing practical advice on appropriate methodologies. The number of countries making guidance available to officials has increased from 10 in 2014 to 26 in 2024 (68% of OECD countries) (Figure 8.9). Guidance can also be used to set expectations and quality criteria, such as a thorough assessment of policy objectives, to maximise the value of ex post evaluations across the administration.
