Joined Cases C-78/16 and C-79/16, Giovanni Pesce (et al) v Presidenza del Consiglio dei Ministri, [2016] EU:C:2016:428. In Xylella, the Court of Justice of the European Union (CJEU) was called upon to assess how far policymakers can go in conditions of scientific uncertainty, and whether EFSA opinions can be indirectly subject to judicial review, despite not being legally binding. In particular, the Xylella case highlights the relevance of EFSA's scientific authority over the Commission: since EFSA opinions are not directly reviewable by the CJEU - as they constitute an intermediate stage of a more complex administrative procedure - the political and legal liabilities relating to EFSA assessments are entirely shifted onto the Commission, whose discretion is reviewable by the EU judiciary. In this regard, the Xylella case confirms how difficult the judicial review of precautionary measures can be. It shows once again that a full assessment of these measures is impossible, as scientific uncertainty restricts the grounds for judicial review to the manifest appropriateness of the contested measures and the availability of less onerous and equally effective measures.