Today the Supreme Court will continue its historic examination of gay marriage with arguments over the Defense of Marriage Act. While the Court’s ruling on Prop 8 has the potential to set in motion a process that would ultimately result in marriage equality being the law of the land everywhere, the DOMA outcome actually may end up being the more consequential one.

Here’s why. If the Court issues a narrow procedural ruling in the Prop 8 case, that will mean that gay rights advocates will have to continue to fight this battle from state to state. And that is where the DOMA ruling comes in.

The DOMA case involves a narrower question than Prop 8 does — whether the federal government can deny benefits to same sex couples married legally in states on the basis of its definition of marriage as between a man and a woman. But in some ways the arguments today will attack the big questions at the heart of this battle every bit as directly as yesterday’s did. That’s because the arguments will provide a clue to the Court’s thinking on “heightened scrutiny.”

The argument over “heightened scrutiny” focuses on a basic question: How much of a burden is there on the government to justify on a policy basis the decision to discriminate against one class of citizens, and at what point does such discrimination become a violation of their constitutional rights? This is about as fundamental to the larger argument over gay marriage as you can get.

When the Obama administration announced that it would no longer defend DOMA in court, Attorney General Eric Holder wrote that the administration believes laws that based on sexual orientation classifications must be subjected to “heightened scrutiny” — i.e., its policy rationale must clear an extremely high standard — and on that basis it violates the Constitution’s equal protection clause. Does the Court agree? As Holder wrote:

The Supreme Court has yet to rule on the appropriate level of scrutiny for classifications based on sexual orientation. It has, however, rendered a number of decisions that set forth the criteria that should inform this and any other judgment as to whether heightened scrutiny applies: (1) whether the group in question has suffered a history of discrimination; (2) whether individuals “exhibit obvious, immutable, or distinguishing characteristics that define them as a discrete group”; (3) whether the group is a minority or is politically powerless; and (4) whether the characteristics distinguishing the group have little relation to legitimate policy objectives or to an individual’s “ability to perform or contribute to society.”

And so, today we’ll hopefully gain some insight into the Court’s thinking — particularly that of swing vote Anthony Kennedy — on whether laws that discriminate in this fashion need to clear an extremely high bar. If the Court strikes down DOMA on this basis, that will provide gay advocates with a powerful weapon to challenge other state laws banning gay marriage. While a broad ruling in Prop 8 would be the best outcome, such a victory on DOMA could also prove consequential.

In the end, as Dana Milbank aptly put it, the only outstanding question on gay marriage is “whether the court forces gay-marriage activists to win the right state by state.” A good ruling on “heightened scrutiny” could help this process along even without any declaration of a Constitutional right to marry.

* Gay rights advocates will likely win on Prop 8: Prominent gay rights advocate Richard Socarides notes that even if the court rules narrowly on Prop 8, meaning even if its ruling doesn’t carry national implications, it’s still all but certain that the measure will be struck down. Returning gay marriage to California is itself a big win:

Right now, the nine states, plus the District of Columbia, that allow same-sex marriage represent approximately sixteen per cent of the population. So the addition of California would mean that almost twenty-eight per cent of the U.S. population—more than one in four Americans — would live in jurisdictions that recognize same-sex marriage. It would also likely give further impetus to the half-dozen or so states on the verge of adopting marriage equality.

* People really like President Obama: A new Washington Post/ABC News poll finds that Obama’s favorability rating is sitting at 57 percent — largely undiminished from after his second inauguration — suggesting he is not taking much of a beating from the sequester standoff. It’s true that Obama’s approval ratings are lagging behind his personal ratings. But likeability could prove an asset as the sequester battle drags on, particularly since Congress is viewed favorably by fewer than one in three Americans.

 * Republicans hate sequester cuts — in their own districts: TPM rounds up all the GOP lawmakers who are suddenly upset about sequester cuts, now that they’re taking hold in their own districts. As noted here the other day, even Tea Party warrior queen Michele Bachmann is decrying these cuts. Republicans cannot sustain their claim that the sequester is a “victory” for them when that “victory” impacts their own constituents. This battle could go either way, but GOP triumphalism is premature.

 * Background checks are not a huge threat to your liberty: Gabrielle Giffords’ gun control group is out with a new Web video that shows her husband buying a gun and undergoing a background check, which is required in the state of Arizona. The video shows the procedure is not a threat to the liberty of the law abiding and is a no brainer when it comes to making it harder for criminals and the mentally ill to get guns — which is precisely why opponents have no choice but to keep lying about it.

* No end to the skittishness from red state Dems: This is striking. Six red state Democrats — Donnelly, Hagan, Heitkamp, Manchin, Pryor, Baucus — voted in favor of an amendment that would require two-thirds of the Senate to pass any gun control legislation. Since the measure is nonbinding, one can only hope these Dems giving themselves cover to do the right thing and ultimately support expanding background checks, which most of them are still refusing to do.

* Obama group joins push for state level campaign finance group: Obama’s reconfigured campaign arm, Organizing For Action, which has been criticized for lack of donor transparency, is mobilizing behind a push in New York for a major overhaul of campaign finance law, including public financing of candidates. The move will test OFA’s capacity for influencing state-level legislative action, but it’s also a reminder of the lack of action on campaign finance reform on the national level, where anything even remotely as ambitious is an all but certain non-starter.

* Progressives need to focus on state legislatures, too: Relatedly, Democracy for America, the group run by Jim Dean (brother of Howard), is launching a new push to take back state legislatures across the country. Dean notes that for all the talk about how the GOP is in trouble nationally, the party controls a lopsided number of state legislatures, where continues implementing regressive social and economic policies. If you need further proof progressives need to look beyond D.C., just look at all the ways we’re still dealing with the consequences of the GOP’s 2010 state level gains.

* And the widening “moral circle” on gay marriage: A must read from Matt Miller on why public attitudes on gay marriage are shifting so quickly:

Today we all have friends, colleagues and relatives who are gay. That’s the way societies change. The moral circle widens. The boundaries of empathy expand. This was the genius of the strategy in Harvey Milk’s passionate refrain on Gay Freedom Day almost 35 years ago: “Come out . . . come out . . . come out.” Despite the pain and risk, Milk knew that once enough gay men and women found the courage to stand up, it would became impossible to sustain bigotry or defend discrimination.

ICYMI: My personal take on the widening moral circle.