The Incorporation Doctrine
By its express terms, the Bill of Rights applies only to the federal government. However, the 1st Amendment and most of the remaining amendments in the Bill of Rights apply to state governments today because of the judicially created “Incorporation Doctrine”.
Beginning in 1925, the justices gradually incorporated the provisions of the Bill of Rights into the 14th Amendment's "due process" clause by declaring that each of the rights was "fundamental" to the conception of due process of law.
The Supreme Court explained the incorporation doctrine in the landmark case of Gideon v. Wainwright. 372 U.S. 335 (1963). The Gideon Court described the 14th Amendment as embracing those "fundamental principles of liberty and justice which lie at the base of all our civil and political institutions." See Gideon 372 U.S. at 340.
Justice Black, writing for the Gideon Court, outlined the incorporation doctrine of the 14th Amendment:
"This Court has looked to the fundamental nature of original Bill of Rights guarantees to decide whether the Fourteenth Amendment makes them obligatory on the States. Explicitly recognized to be of this "fundamental nature" and therefore made immune from state invasion by the Fourteenth, or some part of it, are the First Amendment's freedoms of speech, press, religion, assembly, association, and petition for redress of grievances. For the same reason, though not always in precisely the same terminology, the Court has made obligatory on the States the Fifth Amendment's command that private property shall not be taken for public use without just compensation, the Fourth Amendment's prohibition of unreasonable searches and seizures, and the Eighth's ban on cruel and unusual punishment." See Gideon 372 U.S. at 341-42.
The Court further discussed the incorporation doctrine Pointer v. Texas, 380 U.S. 400 (1965).
Justice Harlan, in his concurring opinion noted:
"The philosophy of "incorporation," . . . subordinates all such state differences to the particular requirements of the Federal Bill of Rights . . . and increasingly subjects state legal processes to enveloping federal judicial authority. "Selective" incorporation or "absorption" amounts to little more than a diluted form of the full incorporation theory. Whereas it rejects full incorporation because of recognition that not all of the guarantees of the Bill of Rights should be deemed "fundamental," it at the same time ignores the possibility that not all phases of any given guaranty described in the Bill of Rights are necessarily fundamental." See Pointer 380 U.S. at 409.
The "total" or “full” incorporation theory has never commanded a majority of the Court. Although Justice Black maintained that one of the chief objects of the 14th Amendment was to make the Bill of Rights applicable to the states, the historical record is ambiguous and the court has opted for "selective" incorporation. At this point, the only provisions of the first eight amendments that have not been incorporated are the 2nd and 3rd Amendments, the 5th Amendment’s requirement of grand jury indictment, and the 7th Amendment. The remainder has been expressly incorporated into the 14th Amendment via its due process clause and so now applies to the state as well as the federal government.