A more thorough explanation:

The Commerce Clause is a part of the United States Constitution that gives Congress the power to regulate commerce between states, with foreign nations, and with Indian tribes. This clause has been used by Congress to pass laws that affect the activities of states and their citizens.

For example, in 1990, Congress passed the Gun-Free School Zones Act, which made it illegal to carry a gun within 1,000 feet of a school. The law was challenged in the case of United States v. Lopez, where the Supreme Court ruled that Congress did not have the power to regulate guns in schools because it did not have a substantial effect on interstate commerce.

However, in other cases, the Supreme Court has taken a broader interpretation of the Commerce Clause. For example, in the case of Wickard v. Filburn, the Court ruled that Congress could regulate the amount of wheat a farmer could grow for personal use because it could affect the overall supply and demand of wheat in the country.

The Commerce Clause has also been used to prevent states from passing laws that discriminate against or excessively burden interstate commerce. For example, in the case of West Lynn Creamery Inc. v. Healy, the Supreme Court struck down a Massachusetts state tax on milk products because it discriminated against non-Massachusetts citizens and businesses.

Overall, the Commerce Clause is an important part of the Constitution that has been the subject of ongoing debate and interpretation.