Before the adoption of the 14th Amendment, the protections in the Bill of Rights limited only the actions of the federal government, unless the provision specifically stated otherwise. The Supreme Court, in what is called “the doctrine of incorporation,” has since its adoption in 1868 interpreted the 14th Amendment to apply most provisions in the Bill of Rights against state and local governments as well. This has meant that the 14th Amendment has been used more frequently in modern court cases than any other constitutional provision and greatly expanded protections for individual rights and liberties.
www.justicelearning.org, The United States Constitution, what it says, what it means, A Hip Pocket Guide (Oxford University Press)