Actually, business process modeling presents an important issue for public institutions. However, due to the high complexity of public processes and their characterizing requirements, such as legal one, appropriate modeling languages are not really available yet. In this work, we propose an extension of one of the most useful modeling language, namely Business Process Modeling Notation (BPMN), to support legal requirements.Keywords: Business Process Management (BPM); Process Modeling; Business Process Modeling Notation (BPMN); Public Processes; Legal Requirement