Definition - What does Commerce Clause mean?
The Commerce Clause is the name given to the clause in the U.S. Constitution that allows federal legislators to regulate business. Specifically, this clause permits Congress to regulate participation in this activity with other countries and with "Indian Tribes."
Historically, it has been controversial because it also subjects participation in business between the states to Congressional regulation.
Justipedia explains Commerce Clause
By granting Congress the authority to oversee commerce between the states, the Commerce Clause restricts state powers. It does so by ensuring that state lawmakers create fair rules with regard to trade. Specifically, it prohibits the creation of rules that benefit businesses within state borders at the expense of those from other states.
For example, the Commerce Clause would prevent legislators in a state with a booming tire manufacturing industry from passing laws that restrict retail tire sales to products that are made there.