Reserved powers are defined as powers assigned to the states and the people. The Tenth Amendment of the United States Constitution covers the subject of reserved powers.
While some powers are assigned to specific political authorities in the Constitution, reserved powers are basically unwritten or unassigned. According to the Constitution, these powers lie with the state governments but only pertain to powers not prohibited by individual state laws or those already delegated in the Constitution. Some examples of reserved powers used by the states include same-sex marriage laws, the establishment of local governments and political campaigns or elections. Reserved power in the United States was first used in 1838. In other countries, including Canada, reserved powers lie within different levels of government.