Dormant Commerce Clause
Origin of the doctrine

If Marshall was suggesting that the power over interstate commerce is an exclusive federal power, the Dormant Commerce Clause doctrine eventually developed very differently: it treats regulation that does not discriminate against or unduly burden interstate commerce as a concurrent power, rather than an exclusive federal power, and it treats regulation that does so as an exclusive federal power. Thus, the modern doctrine says that congressional power over interstate commerce is somewhat exclusive but "not absolutely exclusive". The approach began in the 1851 case of Cooley v. Board of Wardens, in which Justice Benjamin R. Curtis wrote for the Court: "Either absolutely to affirm, or deny that the nature of this power requires exclusive legislation by Congress, is to lose sight of the nature of the subjects of this power, and to assert concerning all of them, what is really applicable but to a part." The first clear holding of the Supreme Court striking down a state law under the Dormant Commerce Clause came in the 1873 case Reading Railroad Company v. Pennsylvania.
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