What is being reserved on amendment 10

Tenth Amendment - Reserved Powers

Explanation:

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.

Six years ago the supreme court resserected the 10th amendment, citing it in an opinion that said congress could not require state and local governments to pay their employees federal wage and hour standards. The federal government appealed and unanimously the supreme court reversed.