Carlos Arrebola and Ana Julia Mauricio (PhD students at the University of Cambridge)

It is widely claimed, especially in publications like The Guardian, that Advocate Generals significantly influence the European Court of Justice (ECJ)’s decisions. This belief is also prevalent among legal professionals specializing in EU law. However, there is limited empirical evidence to support this assumption. Our research investigates whether this perceived influence is accurate or merely a misconception. This question is particularly important as the number of Advocate Generals and the ECJ’s workload increases. Our study, “An Econometric Analysis of the Influence of the Advocate General on the Court of Justice of the European Union,” explores this relationship.

A key challenge in our research was defining terms like “influence” and “following.” For instance, should aligning outcomes between the Advocate General and the ECJ be considered “following,” even if their legal reasoning differs? What if a case has a clear solution, making it difficult to deviate from? Would that indicate the ECJ is following the Advocate General, or simply deciding independently? These questions highlight the difference between correlation and causation.

Our study aimed to establish causation: how often the ECJ decides based solely on the Advocate General’s opinion, as opposed to other factors. This approach allows us to measure the Advocate General’s actual influence. We tested the hypothesis of Advocate Generals’ strong influence against the possibility of a more dialogic relationship with the ECJ. While existing literature suggests a 70% correlation between their opinions and the ECJ’s judgments, this doesn’t necessarily imply causation.

To investigate this, we collected data from 20 years of annulment actions brought before the ECJ. Beyond the Advocate General’s suggestion and the final case outcome, we considered factors potentially influencing the ECJ’s decisions. This included the clarity of the case solution, the subject matter (as some EU law areas are less controversial), and variables related to the Advocate General, the claimant, the court composition, and the type of act under review. By incorporating these variables, we aimed to isolate the Advocate General’s influence from external factors.

While acknowledging limitations in capturing all potential variables, such as a judge’s mood, our econometric study and regression models offered a robust measure of influence. Our findings show a statistically significant result: the ECJ is 67% more likely to annul an act if the Advocate General recommends annulment compared to dismissal or inadmissibility.

These findings confirm the Advocate General’s significant role in the ECJ, influencing EU law development. However, this raises further questions regarding judicial independence. For instance, if Advocate Generals’ opinions heavily influence the ECJ’s decisions, can the court be considered truly independent? Does the public knowledge of the Advocate General’s identity in each case impact their insulation from external pressures? Our article briefly discusses these issues, aiming to provide an evidence-based foundation for future discussions and potential judicial reforms.

Barnard & Peers: chapter 10

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