Which power does the Constitution specifically deny to the federal government?

A. The power to tax citizens

B. The power to ratify changes to the Constitution

C. The power to sign treaties with other countries

D. The power to regulate interstate commerce

One of the limits of the federal power is that the constitution prohibits the federal government to sign treaties with foreign nations by themselves. The Congress, most specifically the Senate, should be involved in making agreements with other countries. It is said in the constitution that " [The President] shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur."