Here are some useful presentations on how to use Case Management Modeling Notations to model legal cases and procedures. Camunda BPM 7.2: CMMN Case Management (English) from camunda services GmbH Discovery and Analysis for Case Management from Denis Gagne
Modelio, open source tool to model processes
Modelio Open Source Community offers a free tool to make models of processes, in a coded-up format. Modelio is an open source modeling environment (UML2, BPMN2, …). Based on a 20-year track record of high end commercial products, Modelio delivers a broad-focused range of standards-based functionalities for software developers, analysts, designers, business architects and system architects