According to Tenth Amendment to the Constitution: "the powers not delegated to the United States, nor prohibited by it to the States, are reserved to the States respectively, or to the people." This would seem to be an unambiguous statement that the federal government can only exercise the powers expressly given it in the Constitution. This rather broad amendment is blurred considerably by what are called implied powers - those powers that, while not expressly given to the federal government, are implied in the Constitution, primarily through the necessary and proper clause (Article I, Section 8, clause 18). This article, interpreted liberally by using the commerce clause expansively, can be interpreted to grant the federal government jurisdiction in a wide range of activities never explicitly mentioned by the founding fathers.
.
.