Exploring the role and content of the safety case

The requirement for dutyholders to produce safety cases (SC) has been adopted in the regulation of major accident hazard industries in the UK. The introduction of a goal setting safety regime stimulates re-appraisal of how safety is controlled and managed. However, the present situation is considered to have shortcomings. Currently, with local variations within different major hazard sectors, it is common for a SC to describe an organization's technical systems and processes and its safety management system (SMS). These sections are accompanied by a risk assessment which attempts to demonstrate that, through these measures and perhaps further identified control measures, risk has been reduced to 'as low as reasonably practicable' (ALARP). This paper criticizes the current norm, accusing it of leading to unbalanced SC that fail to present a complete and strong argument for why the organization's arrangements lead to continuing safe operation. The general weakness identified in current regulations is that they fall short of requiring a dutyholder to present a sound and strong argument. This paper explores the implication of using formal argument models in the development of SC content and considers the implications for the regulator and the dutyholder. Also considered is the degree to which the proposed approach is implemented in other fields such as insurance, aerospace and defence.