The invalidation of the Data Retention Directive is considered as a positive development for the protection of the fundamental rights to privacy and data protection of European citizens and is important for giving an interpretation of these rights in light of the proportionality principle. This paper takes as a starting point the proportionality test as used by the Court of Justice of the EU in its decisions and assesses whether this test is properly defined to accommodate technology developments and the increased surveillance of citizens with devices that are not originally built for the purpose of surveillance (e.g. mobile phones, computers/internet, GPS devices, etc.) and with data that are not originally collected for the purpose of dataveillance. The paper contributes to the existing debates on striking a balance between security and fundamental rights by introducing the so far neglected discussion of the nature of the devices used for surveillance. Due, not only to the level of intrusiveness, but also to the lack of proper legal safeguards for these (non-purpose built but surveillance-ready) devices, it is argued that the proportionality test elaborated by the Court in the Data Retention Directive case is not accurate as long as it does not take the nature of technology used for surveillance into account.