The opening of data is considered to provide many benefits. However, opening up data by public bodies is a complex and ill-understood activity. Although many public bodies might be willing to open up their data, they lack any systematic guidance. In this paper, guidance is provided by investigating the publishing processes at the Dutch Research and Documentation Centre (WODC), which owns governmental judicial research data. We developed guidance by providing 1) a list of issues that play a role in deciding whether to open data, 2) an alternative to completely publishing data (i.e. restricted access) and 3) solutions for overcoming some of the issues. The latter include dealing with privacy-sensitive data, deletion policies, publishing after embargo periods instead of not publishing at all, adding related documents and adding information about the quality and completeness of datasets. The institutional context should be taken into account when using the guidance, as opening data requires considerable changes of organizations.