It is the responsibility of a doctor to treat each patient with the highest quality of care possible. It is not expected that a doctor will save the life of every patient. In software engineering, programmers are expected to ensure the adequate safety of the programs they write. However, they are required to guarantee a result. Unlike doctors saving patients , it is expected that the programs they write will not fail. The responsibility of ensuring the required integrity level falls upon the contractor, who has a duty to advise the client accordingly.