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 sanction states acting as "market participants", but it lacks power to legislate in ways that violate Article IV. In the 21st century, the dormant Commerce Clause has been a frequent legal issue in cases arising under state laws regulating some aspects of Internet activity. Because of the interstate, and often international, nature of Internet communications, state laws addressing internet-related subjects such as spam, online sales or online pornography can often trigger Dormant Commerce Clause issues. A "negative" or "dormant" component to the Commerce Clause has been the subject of scholarly discussion for many decades. Both Supreme Court Justices Antonin Scalia