Most of the time, that fact that D has complied with industry standards means that he/she cannot be found liable in negligence (i.e., he/she did not breach her duty of care; this is a form of 'defence') (Lord Dyson at ).
However, Lord Dyson goes on to say that there are certain circumstances where you cannot simply rely upon industry standards. He provides an example where industry standards have been purposively lowered due to lobbying by interested parties; or when the case covers an industry sector in which "apathy and fatalism has prevailed"; or when the code has failed to keep up with the latest scientific innovations or technology .
Remember, however, that whilst industry standards are taken into account, they are not 'final'; it is still ultimately up to the Courts to reach a conclusion. In Lord Kerr's dissent, he believes that the relatively reasonable cost of acquiring ear defenders (and D's failure to do this) means that D should have been held liable for the hearing loss of C .