The "privileges and immunities clause" has often been advanced as the only sound basis for the imposition of the Bill of Rights upon the states. That theory has been shot down by the courts over and over, despite the "plain meaning" of the text.
Instead, the courts began, early in the Twentieth Century to assert that certain selected parts of the Bill of Rights should be applied to the states under the "due process clause" of the same amendment. That process was called, "substantive due process". This is obviously hogwash, since substance and process are two different things. The courts have ruled over and over that agents of the state who violate the procedural rights of citizens of the state by violating statutes regarding how things are to be done (i.e., "process") is not a violation of the "due process clause". So, for example, Virginia has a statute that requires an arresting officer to be in uniform and displaying his "badge of authority". There is also a statute that requires that each police department have "a uniform". Well, the word, "UNI-form" means a single mode of attire, that will be alike for everyone. Not just an officially designated suit of clothes. A police department is not entitled to have multiple suits of clothes for police officers, and if there are multiple suits (traffic cop, swat team, etc.), then there is no single "uniform". Hence, every arrest by a police officer in Virginia is technically unlawful. A clear violation of the due process clause. But the courts have repeatedly "interpreted" the due process clause to require certain substantive rights, but not that process which is due under the laws of the state. It's amazing to read these cases and see how clever they can be about "interpreting" their way around the text.
Now, here's the kicker: "substantive due process" was a matter of "selective incorporation" until recently. That meant that certain identified rights contained in the Bill of Rights were deemed to apply to the states via the due process clause of the 14th Amendment if, as, and when, the U.S. Sup. Ct. said so. In doing so, the courts routinely assumed that the "rights" applied in exactly the same way to the states as to the federal government. Well, a person has no absolute right of free speech under a state's laws unless the state's constitution specifically says so, or pursuant to statutes. So, for example, in Justice Holmes' famous formulation, "you can't shout 'fire' in a crowded theater". Slander and libel can be regulated. The right to keep and bear arms can be regulated (though not in Virginia, Article 1, Section 13, Const. of Va. - but try telling a court that "shall not be infringed" means "shall not be infringed").
I assert that there is a substantial (though not a "good") reason why the federal courts have gutted the "privileges and immunities" clause entirely, and substituted substance for procedure in the "due process" clause. If the privileges and immunities clause were given real effect, it would require an absolute application of the Bill of Rights to citizens of the states, because the Bill is couched in absolute language. By adopting a method of applying state law to the federal government through the due process clause, the absolute character of the rights enumerated is wiped out; the rights are now subject to "reasonable regulation".
The governmental structure defined by the Constitution requires two different kinds of government with different powers and sovereignty. The state and federal governments are two different kinds, not levels, of government. The federal courts have "interpreted" the Constitution in such a way as to maximize the power of the United States with respect to both the states and the citizens.
Now consider the recent decision in Heller v. the City of Washington, generally hailed as a big victory for 2nd A. advocates. What that decision really did is to cancel out the "selective incorporation" doctrine and substitute a theory that says that the Bill of Rights applies to the states unless there's some powerful reason for excluding some part. But notice Justice Scalia's use of the phrase, "subject to reasonable regulation". What he's done is to put the final nail in Federalism's coffin, and he used the 2nd A. as the trojan horse he used to get us to buy into it. It was a trick. If your rights are subject to reasonable regulation, as someone else defines "reasonable", then you have no rights, no rights at all. That decision stands for the proposition that a citizen has no rights as against the federal government.
The process began with Marbury v. Madison, which had nothing to do with the principle of judicial review (a concept invented in England by the Court of King's Bench centuries earlier), and which stands for the proposition that the Constitution, rather than the charter and basis of federal law, is itself federal law, and thus means whatever the United States says it means. We had a war over that principle, when we decided who gets to decide what "property" is. As far as the law is concerned, that issue is now safely put to rest. You have no rights except what the United States, in its infinite mercy and largess, may decide is "reasonable".
That's why the United States Supreme Court has decided, and repeatedly decreed, that the privileges and immunities clause doesn't mean anything.
