eGovernment has become reality: Most governmental organisations offer electronic services to citizens through the Internet. However, inter-organizational collaboration, especially by means of workflows, is not as widespread. To foster transparency and control in collaborative workflows according to global policies, such as European law regulations, collaborative partners have to partially provide insight into local events and workflows to comply to the global regulations. An example collaboration between Eurojust and Europol emphasises the shortage of existing collaboration architectures lacking the desired control and transparency capabilities needed for the application domain of human-centric eGovernment workflows. To address this, we propose an architecture of a modular runtime infrastructure for decentralized, collaborative eGovernment workflows, hereby respecting the heterogeneity of the system and application landscapes in place.