Glossary · Evidence, assurance and traceability
Assurance case
In systems assurance, an assurance case is a structured argument, supported by evidence, that a system is acceptably safe for a defined application and environment. It links a top-level claim through subclaims and reasoning to the evidence.
- Systems engineering
- Verification
In one sentence
An assurance case is a structured, evidence-backed argument that a system is acceptably safe for a defined application and environment.
Example
For a fleet of AGVs in a warehouse, the assurance case argues from “the AGVs are acceptably safe in this facility” down to subclaims on speed limits, scanner fields and operator training, each backed by test and review records.
How it applies
- Evidence: An assurance case makes the reasoning explicit. Reviewers can see which claims rest on which evidence and where assumptions enter.
- Notations: Goal Structuring Notation (GSN) and Claims-Arguments-Evidence (CAE) are common graphical notations. A structured text document can serve the same purpose.
- Technical documentation: Machinery law does not require an assurance case by name. It can still organize the technical file by showing how requirements, risk assessment and test reports fit together.
- Scope: The conclusion is only valid for the defined application and environment. Changes outside that scope need a revised case.
Assurance case vs. safety case
A safety case is an assurance case whose top claim is about safety. Assurance cases can also address security, reliability or other properties.