The EU has evaluated the data retention directive (DRD) and come to the conclusion that is serves its purpose and is working efficiently. However if one looks at the draft report (via vorratsdatenspeicherung.de), a few questions remain, mainly concerning the methods of the evaluation and some particular statements.
As a consequence, the evidential value of retained data must be assessed on a case-by-case basis in the light of all the relevant factors of a case. ….. Since law enforcement resources are limited the fact that retained data are used, signify they were deemed relevant. …. The retention of data is considered proportionate if it has considerable law enforcement relevance. (pp. 7)