In Industry Standards, Technology Associates, the forensic engineering expert witness company discusses cases where there may be no significant amount of “good” custom and practice within an industry.
…where there is no good custom and practice within the industry, the need for dispassionate engineering judgment is even greater. Further, the engineer should be familiar with relevant techniques outside of the industry in question, so as to determine whether such techniques can be used to improve custom and practice within the subject industry. As a case in point, consider the application of a “dead-man” control to lawnmowers, for the purpose of automatically stopping the rotating blade when the operator takes his hands off the push-bar, for clearing a clump of grass which has become lodged in the structure of the lawnmower at a point dangerously near the blade. The dead-man concept, although long used in other types of machinery, has only recently received substantial (and badly needed) acceptance in lawnmowers.
In summary, in contrast to formal standards as defined above, an industry standard based on custom and practice may be relatively indefinite, requiring engineering analysis, judgment and explanation (especially in the area of human factors) in order to be used as a valid criterion for safe design and practice.