Safety Case Arguments

A safety case regime provides a comprehensive framework within which the duty holder's arrangements and procedures for the management of safety can be demonstrated and exercised in a consistent manner. In broad terms the safety case is a document - meant to be kept up to date - in which the operator sets out its approach to safety management system which it undetakes to apply it. It is, on the one hand, a tool for internal use in the management of safety and, on the other hand, a point of reference in the scrutiny by an external body of the adequacy of that management system - a scrutiny which is considered to be necessary for maintaining confidence on the part of the public. The Rt Lord Cullen (2001).

The process of managing safety, health, and environmental issues in large and/or complex processes and organisations usually requires a formal management system generally referred to as a safety management system (SMS). The argument as to why such a system is to be considered sound is usually referred to as a safety case. The combination of SMS and its justifying arguments are usually known as the 'safety case regime'

A common law safety case is a documented demonstration by an organisation that all statuory, regulatory and common law requirements have been met. It consists of a number of arguments that demonstrate that all reasonable practicable precautions are in place. A common law safety case essentially ensures that due diligence is (seen to be) demonstrated, not that accidents / incidents won't happen.

The move towards common law safety case appears to be as a result of the adversarial legal system. Employers in Australia have a common law duty to provide a safe workplace for employees and the obligation of owners and occupiers of premises to ensure they are safe with respect to members of the public and the surrounding environment. Failure to ensure such may be negligent, and can lead to the significant costs associated with common law claims. It may also lead to statutory penalties for 'responsible' individuals depending on local legislation and regulations.

In order to meet this common law duty of care, it would appear that risk management is shifting away from the concept of 'acceptable' risk to 'not intolerable' risk. If an identified risk is found to be 'intolerable', that is prohibitively dangerous then the activity must be stopped. The concept that risks can only be 'tolerable' (meaning 'not intolerable') seems to be supported in the 2004 revision of the Risk Management AS/NZS 4360:1999 which appears to have deleted all reference to the term 'acceptable' risk.

For risks not identified as 'intolerable', the common law principle applies, that is, the balance of the significance of the risk verses the effort required to reduce it. This is represented by the diagram opposite adopted from Sappideen and Stillman (1995). This means that there is no lower limit to risk.

Any argument that an expert witness could formulate after an event needs to be considered prior to the event.

Arguments to show due diligence are summarised in the diagram opposite and detailed in the Engineers Australia Safety Guide Guideline on-line available from Engineers Media at www.engineersmedia.com.au/bookshop/epub.html.

Each of the methods has different strengths and weaknesses depending on the culture of the organisation and the nature of a particular task.