The highly anticipated cases -- United States v. Windsor March 27 and Hollingsworth v. Perry March 26 -- have stirred effusive national interest over whether the court will definitively rule on the legality of same-sex marriage. But the direction of both days of oral arguments focused little on what the definition is and more on who has the authority to define it.

As it did the day before, questioning from the justices reflected skepticism about the law being reviewed. Justice Anthony Kennedy, who often holds the deciding vote in close cases, joined Justices Stephen Breyer, Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan in suggesting the Defense of Marriage Act, or DOMA, creates two classes of marriage in the country, those recognized by the federal government and those that are not. Ginsburg described the difference as that between regular milk and a "skim-milk marriage."

DOMA was passed by Congress and signed into law in 1996. It said no state or political jurisdiction is required to recognize a same-sex marriage from another jurisdiction. Its Section 3 defines marriage as between one man and one woman for the federal government's purposes, such as for Social Security benefits, federal programs, and federal estate and income taxes.

In 2011, when a handful of states had legalized same-sex marriage and about 30 had banned it, the Obama administration announced that the attorney general had determined that Section 3 is unconstitutional as applied to legally married same-sex spouses. The administration said federal agencies should continue to enforce the law, but that the government would no longer defend it in court.

The court spent nearly a full hour considering the unusual situation of DOMA being defended before the court by members of Congress, not the federal government, which typically would defend a federal law. The court could decline to rule on the merits of the case, by finding that the members of Congress lack jurisdiction over how a law they pass is enforced.

Because the administration is not defending DOMA, its defenders in this proceeding are a group of members of Congress, known as the Bipartisan Legal Advisory Group of the U.S. House of Representatives, known as BLAG.

Vicki Jackson, a Massachusetts attorney appointed by the court to argue against the case for considering the case on the merits of DOMA, told the court that "while it is natural to want to reach the merits of such a significant issue ... this natural urge must be put aside because, however important the constitutional question, Article Ill prevents its decision here and requires this court to await another case, another day, to decide the question."

She noted that the U.S. government got the ruling that it wanted in lower court. Between the two parties involved in the original lawsuit, the U.S. government and Edith Windsor, "there is there is no adversity, they're in agreement, and neither of them is asking this court to reverse or modify the judgment below."

The court also heard from deputy solicitor general Sri Srinivasan, on behalf of the Obama administration's position that the court has jurisdiction to decide the case and Paul Clement, who represented the members of Congress who want the law upheld. Those discussions focused largely on who has jurisdiction to defend a federal law that the administration has decided is unconstitutional, but that has not been overturned.

The court then moved onto the merits of the claim by a New York woman who says she should not have had to pay a higher rate in inheritance taxes because she inherited the estate from her spouse.

While on one level the case is a dispute between a taxpayer and the federal government, on another, the top federal trial lawyer, the solicitor general, is arguing that DOMA is unconstitutional.

The law is being challenged by a New York woman, Edith Windsor, who inherited the estate of her spouse, Thea Spyer, upon her death. The two were partners for more than 40 years and married in Canada in 2007. When Spyer died, Windsor had to pay $363,000 in federal estate taxes. Had her spouse been male, she would have been exempted from that tax.

Much of the discussion in the court went back and forth about whether DOMA's approach of not granting any benefits of heterosexual marriage to those in same-sex marriages is an infringement on states' rights to define marriage.

Paul Clement, attorney for the Bipartisan Legal Advisory Group, said DOMA protects the government from situations that might arise if, for example, a couple in the military was facing a transfer from a state where their same-sex marriage is recognized to a state where it is not.

By keeping federal benefits uniform, the government avoids problems that might arise if such a couple was to resist a transfer to a state without same-sex marriage benefits, Clement said.

Kagan returned several times to questions about the original intent of Congress in passing the law, suggesting the motives were based on bias against same-sex marriage.

She read an excerpt from a House of Representatives report about the law, which said "Congress decided to reflect an honor of collective moral judgment and to express moral disapproval of homosexuality."

Clement acknowledged the remark in the House report, and said "if that's enough to invalidate the statute, then you should invalidate the statute. But that has never been your approach" especially under the legal tests set by the court.

A previous case he cited holds a different example, Clement said, of "Look, we are not going to strike down a statute just because a couple of legislators may have had an improper motive."

The U.S. Conference of Catholic Bishops was among about 30 organizations that filed friend of the court briefs in support of DOMA. Another 45 filed briefs arguing that DOMA should be overturned.

The USCCB said there is "no fundamental right to marry a person of the same sex. ... Specifically, civil recognition of same-sex relationships is not deeply rooted in the nation's history and tradition -- quite the opposite is true."

A day earlier, the court heard oral arguments in another case over same-sex marriage. Hollingsworth v. Perry addresses issues specific to California, where voters in 2008 approved a constitutional amendment barring same-sex marriage a few months after the state Supreme Court said it was unconstitutional to limit marriage to pairs of a man and a woman.

Questioning by the justices raised the possibility that they might toss out that case on the issue of standing, namely whether the people who put the ballot measure together have a legitimate right to stand up for the amendment in court.

Another possibility raised by the justices is that it's too soon for the court to decide whether same-sex marriage is constitutional. Justice Samuel Alito noted that the country had been debating the issue for less time than people have been using cellphones or the Internet.

Rulings in both cases are expected to be issued before the court adjourns for the term in late July.