On page 5 of its petition for certiorari, Virginia states as follows (as part of its "Statement of the Case"):
"The Attorney General of Virginia has the duty to defend the legislative enactments of the Commonwealth. Virginia Code §§ 2.2-507; 2.2-513. When the President signed PPACA on March 23, 2010, the validity of both the Federal and State enactments were drawn into question. If PPACA was supported by an enumerated power, then it would prevail under the Supremacy Clause. If not, the Health Care Freedom Act would be a valid exercise of the police powers reserved to the States. In order to resolve this conflict, Virginia filed a Complaint in the United States District Court for the Eastern District of Virginia for Declaratory and Injunctive Relief."
The precise problem with Virginia's argument (and the rulings of Judge Hudson and Judge Vinson on this point) is the italicized sentence. It is simply wrong that if the ACA is unconstitutional, the Virginia Health Care Freedom Act "would be a valid exercise of the police powers reserved to the States." If Virginia had enacted a law declaring that, as a matter of state law, no Virginia citizen shall be required to acquire health coverage, that would be a valid exercise of the state's legislative authority. But in our federal system, no state has the authority to control federal law, even as it operates within its borders. See McCulloch v. Maryland (on the question of the validity of Maryland's tax, not the discussion of the Necessary and Proper Clause).
Thus, the Virginia Health Care Freedom Act, from its inception, was never--and could never be--a valid exercise of the state's police powers, no matter the constitutional status of the ACA. It was void ad abnitio.
As a result, Virginia cannot possibly have standing to defend the validity, or "enforceability," of its Health Care Freedom Act. The constitutionality of the ACA has no impact on the validity of the Virginia law. The Virginia law is simply invalid regardless, insofar as it attempts to prohibit the regulation of its citizens by the federal government.
Thus, if Virginia has standing, it has to be for some other reason--some indirect way in which it is injured by its citizens' having to acquire health insurance (such as, perhaps, the increase in its Medicaid rolls).