The Incorporation Doctrine is the constitutional principle under which most protections in the U.S. Bill of Rights, originally understood to constrain only the federal government, have been applied against state and local governments through the Fourteenth Amendment. The doctrine's textual basis, and the proper method for determining which rights apply to the states, remain disputed; see incorporation-doctrine-textual-basis-viewpoint and incorporation-doctrine-method-debate.
As applied by the U.S. Supreme Court, incorporation operates primarily through the Due Process Clause of the Fourteenth Amendment, a method generally termed “selective incorporation.” Under this approach, the Court examines provisions of the Bill of Rights individually and incorporates those it deems “fundamental” to liberty or to the American scheme of justice, rather than incorporating the Bill of Rights wholesale. Most provisions have been incorporated; some-including the Third Amendment's prohibition on quartering troops, the Fifth Amendment's requirement of grand jury indictment in felony cases, and the Seventh Amendment's civil jury trial right-have not been ruled applicable to the states. A competing historical argument, associated with the dissents of Justice Hugo Black, holds that the framers of the Fourteenth Amendment intended the Privileges or Immunities Clause to accomplish full, automatic incorporation of the Bill of Rights against the states; this view did not prevail in *Slaughter-House Cases* (1873) but regained scholarly and some judicial attention after *McDonald v. City of Chicago* (2010). See incorporation-doctrine-history and incorporation-doctrine-privileges-or-immunities-viewpoint.
The doctrine's development occurred case by case over more than a century, beginning from a baseline of non-incorporation; for the historical sequence, see incorporation-doctrine-history.