The notion of protected industrial site is only known among those dealing with such companies (employees, jurists, nearby residents, etc). It is a special legal rule that puts enterprises on notice and monitor them when their activities may have a negative environmental impact, through worksites, quarries, farms, factories, etc. It is the industrial sector that raises most of the issues. The first such ruling dates back to 1810, but the landmark ruling of 1976 was of major significance. A nomenclature of activities under environmental threat was introduced and has been regularly updated. The monitoring is carried out by state employees. Protected sites are also self-monitored by companies’ managers under threat of severe penalties if they break the law.