The Law Enforcement Directive (LED) was adopted by the European Union (EU) in May 2016 under the shadow of the General Data Protection Regulation (GDPR). While the official legislative process for the LED started together with the negotiations for the GDPR, in reality negotiations on the LED only genuinely started during the second half of 2015. The LED has by far not achieved all its goals, but it has nevertheless paved the way towards a more coherent and comprehensive framework on the protection of personal data for law enforcement purposes at national level. The growing importance of the LED is also signified by the increasing references of the Court of Justice of the European Union (CJEU) to this Directive. The CJEU has looked into the LED in a number of recent judgements. This panel will explore the interplay between the LED and the GDPR and is going to examine challenges in the application of the GDPR, including (but not limited to) those already raised in current cases in front of or decided already by the CJEU, along with the state of the LED transposition in the EU Member States.