The fifth amendment “due process” was just one of the promises the Bill of Rights gives the citizens against the federal government. The problem is that these promises had no application against the states.
Because of this, in the middle of the 20th century, the Supreme Court issued a series of decisions that incorporated the Due Process Clause and made them applicable to the states.
This way, the 14th amendment ratified this, with the Due Process Clause, that described legal obligations of all states.
