Assurance cases

Assurance cases are a method for providing assurance for a system by giving an argument to justify a claim about the system, based on evidence about its design, development, and tested behavior.

In comparison with assurance based on guidelines or standards (which essentially specify only the evidence to be produced), the chief novelty in assurance cases is provision of an explicit argument. This can allow assurance cases to be more finely tuned to the specific circumstances of the system, and more agile than guidelines in adapting to new techniques and applications.


The main concepts of the Claims-Argument-Evidence (CAE) framework are described here.

One of the advantages claimed of graphical representations such as CAE is that it can represent larger arguments in a form that facilitates comprehension. This is accomplished by chaining argument blocks together, so that the claim of one block becomes a subclaim of another.

CAE Building Blocks

Building blocks represent the types of argument commonly used as individual steps within an argument. Templates and exemplars/fragments provide guidance on composition of these blocks into larger and complete arguments.

There are five main building blocks in CAE, they are summarised in the Building Blocks section of the website.