Yes, we aren't quite finished with Kagan; the open quote is from Dahlia Lithwick:
Republican Version: According to the Sen. Chuck Grassley, R-Iowa, our constitutional rights predate the Constitution itself.
The Court indicates that a "liberty interest" may have either of two sources. According to the Court, a liberty interest may "originate in the Constitution," ante at 427 U. S. 226, or it may have "its roots in state law." Ibid. Apart from those two possible origins, the Court is unable to find that a person has a constitutionally protected interest in liberty.
If man were a creature of the State, the analysis would be correct. But neither the Bill of Rights nor the laws of sovereign States create the liberty which the Due Process Clause protects. The relevant constitutional provisions are limitations on the power of the sovereign to infringe on the liberty of the citizen. The relevant state laws either create property rights, or they curtail the freedom of the citizen who must live in an ordered society. Of course, law is essential to the exercise and enjoyment of individual liberty in a complex society. But it is not the source of liberty, and surely not the exclusive source.
I had thought it self-evident that all men were endowed by their Creator with liberty as one of the cardinal unalienable rights. It is that basic freedom which the Due Process Clause protects, rather than the particular rights or privileges conferred by specific laws or regulations.
Two justices joined in his dissent; later Justice Ginsburg cited the same principle.* This is what Grassley was getting at. The Supreme Court, in a ruling Stevens said he agreed with in part, earlier held that the Second Amendment protects something that "is not a right granted by the Constitution" -- it was a pre-existing one that (like praying to your God) the amendment was written to firmly recognize. After all, slavery too might be a violation of natural rights, but the Constitution recognized its legitimacy in certain contexts.
This need not mean that rights are handed down by God, though clearly many did or still think that. For instance, the 20th Century approach speaks of "the inherent dignity and of the equal and inalienable rights of all members of the human family [a]s the foundation of freedom, justice and peace in the world," but often does so without focusing on God. Rights can grow out of the natural needs and realities of humans. Equality can be a result of equal qualities, such as race not providing relevant differences. Such rights can in some form be considered "natural rights" -- the original form adapted to the realities of the modern age.
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* Other courts and individual judges have cited the Declaration of Independence, again not merely as a freestanding principle, but to flesh out the meaning of constitutional terms. Justice Thomas cited it respecting equality and touched upon it ("natural rights") when fleshing out "privileges or immunities" of citizenship. Again last week. Scalia is the one who did not.