This paper presents a tool for structuring arguments in assurance cases. The tool is designed to support the methodology of Claims-Arguments-Evidence (CAE) Building Blocks that provides a series of archetypal CAE fragments to help structure cases more formally and systematically. It assists with the de-velopment and maintenance of structured assurance cases by providing facil-ities to manage CAE blocks and partially automate the generation of claim structures. In addition to the tool, new visual guidelines called “Helping hand” is provided to assist in applying the building blocks. The tool has been implemented on the Adelard ASCE platform. The target users are assurance case developers and reviewers. The tool and associated methodology can also be useful for people learning how to structure cases in a more rigorous and systematic manner
