Sandefur has an excellent essay on the subject of 14th amendment incorporation and the nature of both privileges and immunities and due process as they apply to both federal and state action. It’s really quite elegantly argued and I agree with this especially:
The second, related point is more fundamental: the Fourteenth Amendment does not say “states must respect the Bill of Rights.” What it says is that no state shall make or enforce any law that deprives people of the privileges or immunities of citizenship, or that deprives them of their rights without due process of law. It is when we ask what the “privileges or immunities of citizenship” are, or when we ask what “due process of law” is, that we must look to the Bill of Rights (among other things!) to guide our understanding. It is for this reason that some provisions in the Bill of Rights do not literally apply to the states. Incorporation can logically be less precise than the actual language in the Constitution, because states are required only to abide by the “due process of law” and respect the “privileges and immunities of citizenship,” which are only imperfectly delineated in the Bill of Rights.
This is really the essence of liberal originalism, the notion that the privileges and immunities of citizenship go beyond what is stated in the Bill of Rights which, as the founders themselves made clear, could not possibly comprise even a reasonable, much less exhaustive, list of all the rights individuals have. The Bill of Rights is not a definitive list of such rights, it is merely a beginning, a brief list of those rights that the founders had seen routinely violated in their day and thus viewed as particularly important. And I even more strongly agree with this statement:
(To understand things this way makes clear that incorporation is really not conceptually distinguishable from what is today derided as “substantive due process.” All due process is substantive. So-called “procedural” due process is only a sub-set of substantive due process.)
Absolutely correct. The distinction between procedural due process and substantive due process is an artificial one; we put procedures in place (like the 4th amendment) in order to protect the principal of substantive due process. You cannot divorce one from the other.