On April 22, 2021 the Advocate General issued its opinion in the proceedings before the Court of Justice of the EU (“CJEU“) under case file no. C-109/20 (“Opinion“). The Advocate General dealt with the question whether an EU Member State can implicitly agree to investment arbitration under a BIT if the EU Member State fails to object to the jurisdiction of the Tribunal. The Advocate General concluded, considering the Achmea Judgment, that such an implicit arbitration agreement would only be compatible with EU law if two conditions are fulfilled: firstly, the award must be subject to a comprehensive review in light of EU law and, secondly, the arbitration agreement must not violate the principle of equal treatment.