When congress chooses to act exclusively in an area in which the states and the national government have concurrent powers, congress is said to have preempted the area.
This is the term that is sued to refer to the powers that exists in the government of the United States that is not left or reserved exclusively for the national government or the state government of the United States. An example is the power to tax.
Hence we can say that: When congress chooses to act exclusively in an area in which the states and the national government have concurrent powers, congress is said to have preempted the area.
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