Clement defended DOMA's constitutionality by saying it was adopted for the sake of uniformity: "it defines the term (marriage) wherever it appears in Federal law in a consistent way."
This intent to "provide uniform treatment of taxpayers" across state lines serves as a "rational basis" for the law, he argued.
However, Solicitor General Donald Verrilli argued against DOMA on behalf of the Obama administration, suggesting that the law should be subject to a higher level of scrutiny because it targets "a class that has undeniably been subject to a history of terrible discrimination."
Verrilli argued the statute is unconstitutional because this discrimination denies equal protection of the law to "married" same-sex couples, but denied that it poses a federalism problem.
Attorney Roberta Kaplan, who agreed with Verrilli in opposing DOMA, did so for different reasons, saying she does not consider the law to be an equal protection problem, but suggested that there is no "legitimate Federal interest that is being served by Congress's decision … to undermine the determinations of the sovereign States with respect to eligibility for marriage."
Discrimination against "married" gay couples was the purpose of DOMA, she argued, and it is "undermining the policy decisions made by those States that have permitted gay couples to marry."
Kaplan said that when DOMA was passed, there was "an incorrect understanding that gay couples were fundamentally different than straight couples."
That understanding "I don't think exists today," she said. "People...now understand that there is no such distinction. So I'm not saying it was animus or bigotry, I think it was based on a misunderstanding of gay people."
But Justice Antonin Scalia questioned Kaplan about her confidence of that judgment, and noted that there has been a "sea change" in public opinion in the years since DOMA was enacted.
When Kaplan reiterated that this change was on the basis of a new "understanding," Roberts responded that this could be attributed to the profound political effectiveness of the gay lobby.
Roberts' point suggests that homosexual people are not a persecuted class who deserve special protections and "heightened scrutiny," as Verrilli's argument had suggested.
(Story continues below)
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Advocates on both sides of the issue will now wait for approximately three months to see how the court will rule in the case, a decision that could have a tremendous impact throughout the nation.