The term Big Data refers to the phenomenon of an ever larger and increasingly complex number of digital data and data files that keep growing in scope continuously and exponentially.1 It is a known fact that worldwide different intelligence agencies employ automated data analysis, known as data mining, on data and data files to understand Big Data and to subsequently target an individual citizen as, for instance, a potential terrorist. Those agencies collect data through the use of methods of mass surveillance. The Snowden affair in relation to the mass surveillance by the American National Security Agency (NSA) is a painful example thereof. More recently, it came to light that the British Government Communications Headquarters GCHQ uses the so-called ‘‘Data vacuum cleaner’’, known as the Karma Police. Using this Data vacuum cleaner, GCHQ intended to create a profile of all internet users in the world and to keep track of how they surf the internet for the purpose of data analysis. Apart from the Big Data data mining by intelligence agencies, more and more also the Dutch police uses automated data analysis of data and data files and real Big Data data mining as a method of investigation in criminal proceedings.2 The automated data analysis by the police can be used (1) to bring up additional personalized data about an individual or individuals who were already labelled as a suspect of a criminal offence and (2) to gather personalized results about a possible suspect or group of suspects. The use of the iColumbo system is an example of Big Data data mining by the Dutch police. Even though Big Data data mining can be a potentially useful and effective method of police investigation, there are some uneasy aspects associated with it. These aspects should be, but so far hardly have been, a topic of discussion in the Netherlands. In this article I will address these uneasy aspects. In this regard, it is first important to emphasise that the process of Big Data data mining, by definition, in most cases also affects data of innocent civilians, and therefore, interferes with the right to privacy of these civilians as protected under the first paragraph of article 8 of the European Convention on Human Rights (ECHR) and articles 7 and 8 of the Charter of fundamental rights of the European Union (the Charter). Second there are several uneasy aspects concerning the use of this method of investigation in criminal proceedings. The question, for instance, arises if there has to be a reasonable suspicion prior to the use of this method in a criminal proceeding. Furthermore, it is relevant which criteria the police is allowed to use for the automated data analysis. Can these criteria also focus on, for instance, data regarding gender, religion and political preference? The question also arises what the value is of the outcome of data mining in criminal proceedings. For example, can a civilian be arrested by the police solely on the basis of the results of automated data analysis?