Volcano of classifying magmatic volcanoes is by their frequency of eruption, with those that erupt regularly called active, those that have erupted in historical times but are now quiet called dormant or inactive, and those that have not erupted in historical times called extinct. However, these popular classifications—extinct in particular—are practically meaningless to scientists. They use classifications which refer to a particular volcano's formative and eruptive processes and resulting shapes. There is no consensus among volcanologists on how to define an "active" volcano. The lifespan of a volcano can vary from months to several million years, making such a distinction sometimes
Dormant Commerce Clause state law under the Dormant Commerce Clause came in 1873. Justice Anthony Kennedy has written that: "The central rationale for the rule against discrimination is to prohibit state or municipal laws whose object is local economic protectionism, laws that would excite those jealousies and retaliatory measures the Constitution was designed to prevent." In order to determine whether a law violates a so-called "dormant" aspect of the Commerce Clause, the court first asks whether it discriminates on its face against interstate commerce. In this context, "discrimination" simply means differential treatment of in-state and out-of-state economic interests that benefits the former and