The general consensus on both the left and the right is that U.S. v. Windsor was a victory for gay rights advocates in particular and liberals in general. On the one hand, Justice Kennedy's opinion affirmed the power of the state governments to define marriage against the power of the Federal Government to interfere; on the other, the opinion striking down The Defense of Marriage Act (DOMA) seems to articulate grounds that will make a constitutional right to gay marriage all but inevitable.
Whether the latter turns out to be true will depend on where five of nine decide to go in the future and on nothing else. I side, however, with Randy Barnett at the Volokh Conspiracy regarding the logic of Justice Kennedy's opinion. It is not at all obvious that it victory for liberals or for gay marriage.
In the first place, the Court clearly does come down on the side of state's rights.
State laws defining and regulating marriage, of course, must respect the constitutional rights of persons, see, e.g., Loving v. Virginia, 388 U. S. 1 (1967); but, subject to those guarantees, "regulation of domestic relations" is "an area that has long been regarded as a virtually exclusive province of the States"…
The significance of state responsibilities for the definition and regulation of marriage dates to the Nation's beginning; for "when the Constitution was adopted the common understanding was that the domestic relations of husband and wife and parent and child were matters reserved to the States."
In the second place, as Barnett observes, Kennedy's opinion introduces a wholly novel trigger for heightened judicial scrutiny and one which depends on the state's power to define and regulate marriage.
Ordinarily, a law need only have a rational basis to pass constitutional muster. That is to say, it must only be a reasonable means to some purpose that is within the powers of government to pursue. So, for example, a speed limit is rationally related to the cause of public safety. When, however, a law seems to violate some fundamental right (due process or equal protection, for example), it triggers strict or at least "heightened" judicial scrutiny. That imposes a very stringent test. The law must serve some compelling purpose and it must be narrowly tailored to that end. When the Court announces that strict scrutiny has been triggered, that usually means that the Court is going to strike the law down.
What is novel in Windsor is that the trigger for heightened scrutiny is not the violation of a constitutional right but the violation of a state-granted right. Kennedy argues that, while a state may be free to define marriage, that definition creates a set of rights and privileges that must be uniform in that state for all married couples. This is where DOMA goes wrong.
DOMA rejects the long established precept that the incidents, benefits, and obligations of marriage are uniform for all married couples within each State, though they may vary, subject to constitutional guarantees, from one State to the next. Despite these considerations, it is unnecessary to decide whether this federal intrusion on state power is a violation of the Constitution because it disrupts the federal balance. The State's power in defining the marital relation is of central relevance in this case quite apart from principles of federalism. Here the State's decision to give this class of persons the right to marry conferred upon them a dignity and status of immense import. When the State used its historic and essential authority to define the marital relation in this way, its role and its power in making the decision enhanced the recognition, dignity, and protection of the class in their own community.
As the Court reads the case, DOMA effectively singles out part of the married population in a same-sex marriage state and denies some of the benefits of marriage to that subpopulation. It does so without identifying a legitimate federal interest in this departure from traditional deference to state laws. That violates the rights of persons in marriages targeted by the law.
I will close with three points. First, this case may indeed be the Griswold in advance of Roe that everyone seems to take it for. I merely point out that the logic of the opinion does not point in that direction at all. Kennedy finds no constitutional right to same sex marriage. Instead, he finds a right to "a dignity and status of immense import" that is uniformly conferred by a State's "its historic and essential authority to define the marital relation."
Second, while the Court found it "unnecessary to decide whether this federal intrusion on state power is a violation of the Constitution because it disrupts the federal balance," the entire decision seems to rest on the power of a state to define marriage and (presumably) restrict that institution to opposite sex couples. That hardly strengthens the hand of those who want a constitutional right to same sex marriage.
Third, DOMA is precisely the kind of legislation that conservatives are supposed to dislike. Apart from the issues of liberty and equal protection, it is a federal meddling in the essential business of the state governments.
I am in favor of legal same sex marriage. I do not, however, confuse my political preferences with Constitutional mandates. I see nothing in the Constitution that requires legal same sex marriage. I think that the states do indeed have the authority to define marriage, subject to certain constitutional restraints. Uniformity seems to me to be a valid restraint. I haven't read the dissents yet, and I usually agree with justices Scalia and Thomas. So far I do not see anything in this decision that I would take issue with.