Digital traces that people leave behind in our digitalized society can be useful evidence in criminal courts. The central question of this article (how is the use of data as evidence in Dutch criminal courts regulated and, considering how these courts deal with such data as evidence in practice, what is needed?) is answered by analyzing the relevant legal frameworks for processing data in Dutch criminal courts: criminal law and data protection law. Next, current court practices are examined, by looking at typical case law and current developments in society and technology. Comparing the legal framework and actual practices, we conclude that the existing legal framework in the Netherlands does not obstruct the collection of data for evidence, but that regulation on collection (in criminal law) and regulation on processing and analysis (in data protection law) are not integrated. Remarkable is the almost complete absence of regulation of automated data analysis – in contrast with the many rules for data collection.