For the purpose of good and trustworthy management information for the government, our research institute has built a data space system that makes it possible to periodically monitor data flows within as well as between organizations of the justice domain. The aim of this system is to get insight into the success and possible bottlenecks in the criminal justice domain. Data from heterogeneous sources are extracted and related by means of domain knowledge. The system consists of three layers: a data space, a space manager and an interface layer. The data space layer consists of a set of heterogeneous databases. The space manager layer -- implemented as a variable database and a relationship module -- consists of domain knowledge. The relationship module decides which databases in the data space layer are required to answer a query. The interface layer consists of a user friendly web interface, which facilitates policy makers to interpret data flows within the justice domain.