The introduction of the UK regulatory concept of 'tolerability' and making risks 'as low as reasonably practicable' (HSW Act; 1974, HSE; 1992a and HSE; 1992b,) has resulted in the need to make 'ALARP arguments' as an essential part of a system safety case. A similar concept is used for the control of pollution which requires the use of the 'Best Available Technology/Techniques Not Entailing Excessive Cost (BATNEEC under the Environmental Protection Act). A parallel international development has been the concept of 'As Low As Reasonably Achievable (ALARA), framed by the International Commission on Radiological Protection. The concept of demonstrating 'reasonableness' in the design, proving and operation of products and systems is the key defence against both civil and criminal litigation.

For Consumer Protection the arguments cover reasonable consumer expectation to reasonable producer competence (was there a reasonable alternative design?) (Consumer Protection Act; 1987, cross reference to relevant chapter/s). The complexity of computer-based systems, which makes complete system specification, testing and/or proving impossible, emphasises the need for a probabilistic (risk-based) approach. This appears to be also consistent with the adversarial UK approach to litigation, where concepts such as "the balance of probabilities" and "reasonable doubt" are traditional.

There are a significant number of standards already in existence or under development aimed at translating these principles into guidance on the design of programmable systems and ways of estimating their reliability. Notable are: IEC 61508, EUROCAE-ED-12B (RTCA/DO178B), DefStan 00-55 and DefStan 00-56. The need for a company to produce a compliant product or system safety-case is a critical part of the design process and representing a major economic risk. Origin has been founded on the basis of resolving these design justification challenges utilisings:

• Low risk deployment of new technologies, including the use of COTS technologies
• Development of systematic approaches to safety argument construction that empower projects to reason about risk and design choices
• Development of infrastructures to allow systematic gathering of evidence
• Development of management approaches to integrate technologies and safety assesment more effectively

HSW (1974) 'Health and Safety at Work etc. Act', HMSO, London 1974

HSE (1992a) 'The Tolerability of Risk from Nuclear Power Stations (TOR)', Health and Safety Executive HMSO, London, 1992

HSE (1992b) 'A Guide to the Offshore Installations (Safety Case) Regulations', Health and Safety Executive HMSO, London, 1992