To regulate commerce with foreign nations, among the several states, and with the Indian tribes; Means what exactly

Commerce Clause

Explanation:

To regulate commerce with foreign nations, among the several states, and with the Indian tribes simply refers to the Commerce Clause. The authorization is given to the Congress to enable them regulate the commerce.

Apart from the authorization that the Commerce Clause gives to the Congress, it also prohibits state laws in scenarios where there's discrimination against commerce between interstate.

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