According to the ever useful Open Europe press summary Germany's constitutional court has ruled that its country's interpretation of EU rules on data retention breach its Constitution

The German Federal Constitutional Court ruled yesterday that the German law implementing the EU's Data Retention Directive breaches the German Constitution. However, the Court ruled against the implementation of the Directive, rather than the Directive itself. The Court ruled that the retention of information is permitted only under strict rules of Constitutional law, if someone's life or freedom were in danger, and therefore all data collected before yesterday's ruling under the Directive must be immediately erased.
 
Prior to this decision, internet providers and telecommunication companies were obliged by the Directive to store telephone numbers, emails and internet connections of all citizens for six months without needing a concrete reason. The judges ruled that the implementation of the Directive provided "neither adequate data security, nor sufficient boundaries on the application of data retention.
 See AP