Equal footing doctrine

This Union' was and is a union of states, equal in power, dignity, and authority, each competent to exert that residuum of sovereignty not delegated to the United States by the Constitution itself. To maintain otherwise would be to say that the Union, through the power of Congress to admit new states, might come to be a union of states unequal in power, as including states whose powers were restricted only by the Constitution, with others whose powers had been further restricted by an act of Congress accepted as a condition of admission.