The IEC 61508 standard is a large specification with each sub-clause being a requirement. The standard states: “To conform to this standard it shall be demonstrated that the requirements have been satisfied to the required criteria specified and therefore, for each clause or sub-clause, all the objectives have been met.”
In the opinion of exida, this statement requires a “Safety Case” or “Safety Justification” to the requirements of IEC 61508. A simple certificate and certification report stating general compliance with a standard does not fulfill the IEC 61508 requirements. A full Safety Case lists all IEC 61508 requirements and provides the arguments and justification as to how each project meets the standard. exida does a Safety Case for each certification project.
In addition, the exida Certification program looks at usability of a product from a systems perspective and evaluates the likelihood of unintended misuse. Although this is not part of many certification programs, the exida End User Advisory Council has strongly suggested this interpretation of IEC 61508 requirements.