The concept of "due process" is a cornerstone of the United States's republican system of government. It states that every citizen is accorded the right to fair and impartial treatment through the judicial system. As such, there are many rules, laws, clauses and doctrines on the books that address due process in various ways. Two of these are the incorporation doctrine through the Fourteenth Amendment to the Constitution and the Fundamental Fairness Doctrine as it applies to everyday law practice.
The incorporation doctrine applies specifically to the relationship between state and federal governance. Early on, courts ruled that the Bill of Rights (the first 10 Amendments to the US Constitution) only applied to the actions of the federal government, but did not limit the authority of state and local governments. (This precedent was set in the 1833 case of Barron v. Baltimore.) The Fourteenth Amendment was then passed in 1868 and, among other clauses, guaranteed equal treatment under the law as part of its "Due Process" clause. Subsequently, a series of cases in the 1920s interpreted the substance of this Amendment to now mean most parts of the Bill of Rights were able to be enforced against states and local municipalities.
The Fundamental Fairness Doctrine, on the other hand, applies to rules of due process within a judicial proceeding and is applicable on the individual level. For instance, it guarantees the right of the individual to have a fair trial with adequate notice to prepare, the right to have attorney representation, the right not to testify against oneself, and the right to confront one's accusers or any witnesses. These rights derive not only from the Fourteenth but the Fifth Amendment as well, and most modern legal professionals declare the doctrine synonymous with the very concept of due process.