What Is a Safety Case

The safety case provides a structured argument, supported by a body of evidence, that provides a compelling, comprehensible and valid case that a system is acceptably safe for a given application in a given context [6]. Let s break that definition down into its component parts. 

The safety case is not a dashboard of data or a set of performance metrics. Its depth and interpretation is much greater and the foundation of the safety case is the concept of a structured argument The articulation of hazard s causes and, importantly, the controls provides a rounded rationale from which any conclusions relating to overall degree of cUnical risk will be drawn. The argument will be underpinned by 

Secondly, stracture provides the reader with a means of evaluating completeness. The goal-based assessment methodology and a number of common risk assessment techniques can occasionally be criticised for their inability to clearly demonstrate completeness. A convincing safety argument may be set out based on the evident facts but how can one be reassured that all credible hazards have been considered The application of structure to an argument facilitates the reader in determining this and perhaps invites their welcome criticism. 

Most HIT safety cases would not typically stand up to the intense rigour of the scientific method. The safety case is not a mathematical proof. Rather it should present the rationale for a reasonably educated reader, through the careful appUcation of logic, to draw justifiable conclusions from the evidence presented. The technique is sometimes referred to as inductive reasoning and is the basis of many scientific theories. 

A compelling case is developed through the rigorous application of process against a target which is appropriately granular and well-defined. Doing so establishes completeness with minimal room for hazards to fall between the cracks and remain hidden. A comprehensible safety case summarises the analysis in a concise 

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Arguably, then, the question is not what is a safety case regime—but rather what kind of safety case regime is being contemplated... 

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