Forecasting Candidate States’ Compliance with EU Accession Rules, 2017–2050

The European Union (EU) is said to be tired of enlargement – but how likely is it that a candidate would be ready to join within 10, 15 or more years? This research forecasts how prospective members are likely able to perform in implementing EU law until 2050. Using compliance data of all states from the 2004, 2007 and 2013 accession rounds, as well as of five current/potential candidates, we construct an empirical model on candidates’ ability to comply with the acquis communautaire. We employ in-sample and out-of-sample techniques to ensure high model prediction accuracy and, ultimately, forecast the five candidates’ potential compliance levels in 2017–2050. Our research shows that only one candidate might sufficiently be able to comply with the accession criteria until 2023, while many are unlikely to be ready before the mid-2030s. Focusing on prediction and forecasting, our contribution is given by the research’s policy relevance and its methodological innovation.