Justice Kennedy, for a unanimous Court, answers this question in the affirmative in Bond v. United States.

In amicus’ view, to arguethat the National Government has interfered with state sovereignty in violation of the Tenth Amendment is toassert the legal rights and interests of States and States alone. That, however, is not so. As explained below, Bondseeks to vindicate her own constitutional interests. The individual, in a proper case, can assert injury from governmental action taken in excess of the authority thatfederalism defines. Her rights in this regard do not belong to a State.

Justice Kennedy waxes quite a bit about the value of federalism, and its relationship to enhancing freedom.

The Framers concluded that allocation of powers between the National Governmentand the States enhances freedom, first by protecting the integrity of the governments themselves, and second by protecting the people, from whom all governmental powers are derived.Federalism has more than one dynamic. It is true that the federal structure serves to grant and delimit the prerogatives and responsibilities of the States and the National Government vis-à-vis one another. The allocation of powers in our federal system preserves the integrity, dignity, and residual sovereignty of the States. The federal balance is, in part, an end in itself, to ensure that States function as political entities in their own right.

However, Federalism does not merely set the boundaries “between different institutions of government for their ownintegrity. ‘State sovereignty is not just an end in itself: ‘Rather, federalism secures to citizens the liberties that derive from the diffusion of sovereign power.’”

Kennedy sees Federalism protecting “liberties [] of a political character,” which “allows States to respond, through the enactment of positive law, to the initiative of those who seek a voice in shaping the destiny of their own times without having to rely solely upon the political processes that control a remote central power.” Federalism “also protects the liberty of all persons within a State by ensuring that laws enacted in excess of delegated governmental power cannot direct or control their actions.”

By denying any one government complete jurisdiction over all the concerns of public life, federalism protects the liberty of the individual from arbitrary power. When government acts in excess of its lawfulpowers, that liberty is at stake.

These interests are not limited to the states but belong to individuals.

The limitations that federalism entails are not therefore a matter of rights belonging only to the States. States are not the sole intended beneficiaries of federalism. See New York, supra, at 181. An individual has a direct interest in objecting to laws that upset the constitutional balancebetween the National Government and the States when the enforcement of those laws causes injury that is concrete, particular, and redressable. Fidelity to principles of federalism is not for the States alone to vindicate.

Somewhere Randy Barnett’s ears are burning:

Separation-of-powers principles areintended, in part, to protect each branch of government from incursion by the others. Yet the dynamic betweenand among the branches is not the only object of the Constitution’s concern. The structural principles secured bythe separation of powers protect the individual as well.

In an interesting passage about the liberty of non-citizens, focusing on INS v. Chadha (a suit brought by a non-citizen).

A cardinal principle ofseparation of powers was vindicated at the insistence of an individual, indeed one who was not a citizen of the United States but who still was a person whose liberty was at risk.

And in a somewhat stunning string of citations, including PCAOB, Bowsher, Youngstown, and Schecther Poultry, Justice Kennedy makes it abundantly clear that “if the constitutional structure of our Government that protects individual liberty is compromised, individuals who suffer otherwise justiciable injury may object.”

This opinion is really opening up the door for individuals to vindicate liberty interests that historically have not been open.

Justice Ginsbug says as much in her concurring opinion.

For this reason, a court has no “prudential” license todecline to consider whether the statute under which the defendant has been charged lacks constitutional applica-tion to her conduct. And that is so even where the constitutional provision that would render the conviction void is directed at protecting a party not before the Court. Our decisions concerning criminal laws infected with discrimi-nation are illustrative. The Court must entertain the objection—and reverse the conviction—even if the right to equal treatment resides in someone other than the defendant. . . . In short, a law “beyond the power of Congress,” for any reason, is “no law at all.” Nigro v. United States, 276 U. S. 332, 341 (1928). The validity of Bond’s conviction dependsupon whether the Constitution permits Congress to enact§229. Her claim that it does not must be considered and decided on the merits

This explains the broad consensus:

Just as it is appropriate for an individual, in a proper case, to invoke separation-of-powers or checks-andbalances constraints, so too may a litigant, in a proper case, challenge a law as enacted in contravention of constitutional principles of federalism. That claim need not depend on the vicarious assertion of a State’s constitutional interests, even if a State’s constitutional interests are also implicated.

Justice Kennedy also elaborates on on the relationship between the national and state powers:

There is no basis to support the Government’s proposed distinction between different federalism arguments for purposes of prudential standing rules. The princi-ples of limited national powers and state sovereignty are intertwined. While neither originates in the Tenth Amendment, both are expressed by it. Impermissible interference with state sovereignty is not within the enumerated powers of the National Government, see New York, 505U. S., at 155–159, and action that exceeds the National Government’s enumerated powers undermines the sovereign interests of States. See United States v. Lopez, 514U. S. 549, 564 (1995). The unconstitutional action can cause concomitant injury to persons in individual cases.

Interestingly, Justice Kennedy expresses no opinion on the Necessary and Proper Clause. Methinks he did this so as not to lose votes.

There is no basis in precedent or principle to deny petitioner’s standing to raise her claims. The ultimate issue of the statute’s validity turns in part on whether the law canbe deemed “necessary and proper for carrying into Execution” the President’s Article II, §2 Treaty Power, see U. S. Const., Art. I, §8, cl. 18. This Court expresses no view on the merits of that argument.