Courts have interpreted the Constitution to allow federal jurisdiction over many functions that are not explicitly mentioned in the Constitution, in contradiction to the literal words of the 10th amendment that "The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people."
Checks and balances
Federal System
The division of powers between the national and state governments called federalism. This division of powers is facilitated by the federal government.
federalism
in the US, the Tenth Amendment to the Constitution
the division of power between the national and state governments
Division of powers
a division of power between state and national governments
great compromise
it forbids laws limiting states' power
The 10th Amendment to the US Constitution established federalism. It distributes the responsibilities of government between local, state, and national governments.
That's what the 2nd Amendment is all about, the last line of defense.