Safety case

One definition of a Safety Case is that it is a structured argument, supported by evidence, intended to justify that a system is acceptably safe for a specific application in a specific operating environment.^[1] Safety cases are often required as part of a regulatory process, a certificate of safety being granted only when the regulator is satisfied by the argument presented in a safety case. Industries regulated in this way include transportation (such as aviation, the automotive industry and railways) and medical devices. As such there are strong parallels with the formal evaluation of risk used to prepare a Risk Assessment, although the result will be case specific. A vehicle safety case may show it to be acceptably safe to be driven on a road, but conclude that it may be unsuited to driving on rough ground, or with an off-center load for example, if there would then be a greater risk of danger e.g. a loss of control or an injury to the occupant. The information used to compile the safety case may then formally guarantee further specifications, such as maximum safe speeds, permitted safe loads, or any other operational parameter. A safety case should be revisited when an existing product is to be re-purposed in a new way, if this extends beyond the scope of the original assessment.