The most significant challenge of the regulatory life cycle occurs after the adoption of a new regulation when its outcomes need to be assessed. To address this challenge, ex-post regulatory evaluation procedures have been developed, where the implementation is examined after a period of time from the regulation's adoption. Ex-post evaluation allows for the assessment of the regulation's results, whether it has achieved its goals, its efficiency, and the manner in which it was implemented and enforced. Although ex-post evaluation is a critical link in the regulatory life cycle, it has not received much scholarly attention and has often been relegated to the margins. This article presents a typology of different models of ex-post regulatory evaluation. We conduct a comparative analysis of how evaluation processes are applied in several countries, including the United States, Italy, the United Kingdom, and Australia. From the comparison, we identify a typology including several forms and approaches to ex-post evaluation. The post-legislative evaluation approach focuses on a formal examination of the completion of the legislative process and the implementation of the regulation, putting it into action. The efficiency evaluation approach primarily examines the cost versus the benefit, aiming to improve economic efficiency and reduce the regulatory burden. The effectiveness evaluation approach examines whether the regulation achieved its goals and whether its implementation led to the desired outcomes. Finally, the participatory evaluation approach emphasises insights derived from those subject to the law, stakeholders, or the public, relying on mechanisms for participation in the evaluation processes. Based on the identification of these different approaches, we outline a proposed multi-layered model for implementing ex-post regulatory evaluation that applies the different approaches reviewed in a stepwise manner.
