Claims, Arguments and Evidence (CAE)
Claims, Arguments and Evidence is a simple yet effective notation for
presenting and communicating your safety argument. Adelard developed CAE as
a straightforward notation for structuring safety cases. It is one of the
key notations available in ASCE.
It allows you to structure your overall argument into the following elements:
Claim - a statement asserted within the argument that can
be assessed to be true or false,
- "System X is adequately safe during the shut down phase of
- "Unit testing is complete"
- "All identified hazards are adequately managed in the hazard
- "Design personnel are suitably qualified"
- "Training materials have been reviewed"
Each claim is be supported by a number of sub claims, arguments or
The claim may contain additional contextual material, for
example explaining terms used and scope.
ASCE contains tools for editing rich narrative at any node in the
Argument - a description of the argument approach
presented in support of a claim. e.g.:
- "argue by considering safety of subsystems"
- "because wiring conforms to relevant electrical standards"
This element is optional, but often it is good practice to include to
explain the approach to satisfying the parent claim
If the approach to supporting a claim is
straightforward or well understood by the intended audience, it is permissible to simply link directly from the
Evidence - a reference to the evidence being presented in
support of the claim or argument, e.g.
- "the hardware reliability analysis report"
- "interlock design documentation"
Usually the evidence node will summarise and link out to the relevant
report containing the evidence
ASCE contains a number of tools to
- linking to, management and tracking of changes in the underlying