The Bill of Rights, ratified in 1791, initially applied only to the federal government. For decades, states retained broad powers to infringe upon individual liberties that the federal government could not touch. This changed dramatically with the adoption of the Fourteenth Amendment in 1868, specifically its Due Process Clause. Through the doctrine of selective incorporation, the Supreme Court has gradually applied most of the Bill of Rights to the states, fundamentally altering the balance of power and expanding individual protections across the nation. This process, far from being a single event, has been a century-long judicial endeavor, reinterpreting constitutional text and gradually extending federal guarantees to state actions.
The foundational step towards selective incorporation began with the ratification of the Fourteenth Amendment, which stated, "...nor shall any State deprive any person of life, liberty, or property, without due process of law." Initially, the Court interpreted this narrowly, viewing it as a procedural safeguard rather than a vehicle for incorporating specific Bill of Rights provisions. The landmark case Slaughter-House Cases (1873) famously held that the Privileges or Immunities Clause did not incorporate the Bill of Rights. However, the seeds of change were sown. It was not until the early 20th century that the Court began to reconsider the implications of the Due Process Clause for state action, particularly concerning economic liberties. Chicago, Burlington & Quincy Railroad Co. v. City of Chicago (1897) marked a significant, albeit early, shift by applying the Fifth Amendment's just compensation requirement for takings to the states, establishing that the Due Process Clause could indeed incorporate protections found in the Bill of Rights.
The true surge of selective incorporation occurred during the 1920s and 1930s. The Court, under Chief Justice Hughes, began to identify fundamental rights that were essential to the concept of ordered liberty. The First Amendment's guarantees of free speech and free press were among the first to be fully incorporated. In Gitlow v. New York (1925), the Court affirmed that the First Amendment applied to the states, stating, "For present purposes we may and do assume that freedom of speech and of the press—which are protected by the First Amendment from abridgment by Congress—are among the fundamental personal rights and 'privileges' which such amendment is designed to protect from state invasion." This decision opened the floodgates. Soon after, freedom of religion was incorporated through Cantwell v. Connecticut (1940), ensuring that states could not prohibit the free exercise of religion or establish a religion.
The process continued with other crucial amendments. The Fourth Amendment's protection against unreasonable searches and seizures was incorporated in Mapp v. Ohio (1961), a pivotal decision that excluded illegally obtained evidence from state trials. This followed earlier cases that had incorporated aspects of the amendment, but Mapp solidified the exclusionary rule's application nationwide. The Sixth Amendment's right to counsel, initially limited to federal cases, was applied to the states in Gideon v. Wainwright (1963), a case that famously resulted in the landmark Supreme Court decision overturning the conviction of Clarence Gideon, a poor and unrepresented defendant. This ruling ensured that indigent defendants in felony cases had a right to legal representation. Further, the Fifth Amendment's protection against self-incrimination was incorporated in Malloy v. Hogan (1964), and the Eighth Amendment's prohibition of cruel and unusual punishments was incorporated in Robinson v. California (1962).
While most of the Bill of Rights has been incorporated, a few provisions remain solely applicable to the federal government. The Third Amendment, prohibiting the quartering of soldiers, and the Second Amendment's right to bear arms are notable examples. The Court has also been less inclined to fully incorporate certain procedural rights within the Sixth Amendment, such as the right to a unanimous jury verdict in all criminal cases, as seen in Apodaca v. Oregon (2012) which allowed for non-unanimous jury verdicts in state criminal trials. The "selective" nature of incorporation means the Court decides on a case-by-case basis which rights are "fundamental" and thus apply to the states.
In conclusion, selective incorporation represents a profound evolution in American constitutional law. It has transformed the relationship between the federal government and the states, creating a national baseline for individual liberties. By applying most of the Bill of Rights to state governments, the Supreme Court has ensured a more uniform protection of fundamental rights, safeguarding citizens from state actions that would have been permissible under earlier interpretations of the Constitution. This ongoing judicial dialogue continues to shape the scope and application of constitutional freedoms.