The rule seems clear enough, but it leaves courts of last instance with significant discretion. (leidenlawblog.nl)
Based on Art. 267 (3) TFEU the courts of last instance of the Member States are obliged to submit EU law questions in the framework of a preliminary ruling procedure to the CJEU. (europeanlawblog.eu)
Should a Member States «court of last instance nonetheless submit a question within the scope of EU law to the ECtHR without being entitled to do so under the acte - clair - doctrine, proceedings for infringement of the Treaties could be engaged against that Member State based on Art. 258 f. TFEU. (europeanlawblog.eu)