It is emphatically the province and duty of the judicial department to say what the law is...If two laws conflict with each other, the courts must decide on the operation of each...This is of the very essence of judicial duty.

The power to tax involves the power to destroy;...the power to destroy may defeat and render useless the power to create.

State inspection laws, health laws, and laws for regulating the internal commerce of a State, and those which respect turnpike roads, ferries, &c. are not within the power granted to Congress. ... Inspection laws, quarantine laws, health laws of every description, as well as laws for regulating the internal commerce of a State, and those which respect turnpike roads, ferries, &c., are component parts of this mass. No direct general power over these objects is granted to Congress, and, consequently, they remain subject to State legislation.

When a law is in its nature a contract, when absolute rights have vested under that contract, a repeal of the law cannot divest those rights.

The constitution is either a superior paramount law, unchangeable by ordinary means, or it is on a level with ordinary legislative acts, alterable when the legislature shall please to alter it. It is emphatically the province and duty of the judicial department to say what the law is. This is the very essence of judicial duty.

Certainly all those who have framed written constitutions contemplate them as forming the fundamental and paramount law of the nation, and consequently the theory of every such government must be, that an act of the legislature, repugnant to the constitution, is void.

Have no power, by taxation or otherwise, to retard, impede, burden or in any manner control the operations of the constitutional laws enacted by Congress.