After the whirlwind that has been the last two days at the Supreme Court, it's hard to point to any outcome in either the Prop 8 case or in Edie Windsor's challenge to the Defense of Marriage Act as more likely than another. There was division on the Court as to the constitutional merits of both laws (unsurprisingly, the liberal Justices tended to express doubt about the laws' validity while the conservative Justices leaned towards upholding them), and there was substantial time devoted to legal and procedural questions that could prevent the Court from even deciding whether the laws are constitutional or not. Here's a brief look at the possible outcomes available to the Court in each case.
The Prop 8 case (Hollingsworth v. Perry)
A dismissal of the case as 'improvidently granted'
Any Supreme Court watcher will tell you that the magic number at 1 First Street is five: with five votes, you can do anything; without them, you can do nothing. That's true of the Court's legal decisions, where five votes are required to create a controlling, majority opinion. But since the high court has discretion over which cases it reviews from the lower courts, there is a different magic number when it comes to whether or not the Court will take up a specific appeal. That number is four, and since four Justices can vote to hear a specific case (the technical term is called 'granting a writ of certiorari), the Court can end up hearing a case that only a minority of Justices want to consider.
At Tuesday's oral arguments, it looked like there might indeed have only been four votes on the Court to take up the Prop 8 case in the first place. Justice Sotomayor specifically mused whether the Court should let the issue of marriage equality percolate in the lower courts, to which Justice Scalia snippily responded that the Court had decided to take the case, so it didn't matter what Sotomayor thought since that decision had already happened. But Justice Kennedy, the über-powerful swing vote, seemed almost eager to avoid the central constitutional questions in the case, asking lawyers on both sides of the issue if the case was properly granted. That could signal that it was only the Court's four conservative Justices who voted in the first place to consider the Prop 8 case, and that there are five votes (the liberals plus Kennedy) for--as the legal terminology puts it--dismissing the case as 'improvidently granted.'
Such a dismissal is uncommon but not unheard of, and it essentially means the Court decides that it was wrong to take up a particular appeal and dismisses the case without any decision on the merits. The significance of such a move is that it leaves the Ninth Circuit's ruling in place, restoring marriage equality to California on the narrow grounds that it was unconstitutional for the state to extend equal marriage rights and then rescind those rights by a popular vote. Such a decision would be binding on everyone in California and would also also stand as precedent in the entire Ninth Circuit, meaning that no other state in the circuit with marriage equality (for now, only Washington) would be able to take away those rights through a ballot initiative.
A decision that the Prop 8 proponents do not have standing
A very significant gateway question in the Prop 8 case is whether the ballot measure's official proponents--who intervened in the lawsuit to defend Prop 8 after the governor and attorney general of California declined to do so--have what is known as Article III standing to defend the law at all. Without getting too lost in the legal weeds, in order to have standing in a federal court, a party generally has to show that they've suffer a specific, personalized injury and are not simply putting forward a claim to some more generalized injury that does nothing to distinguish them from the general public.
When the Ninth Circuit addressed the constitutionality of Prop 8, it asked the California Supreme Court for an advisory opinion on whether the law's proponents had standing under state law to defend the statute in court, and relied on the California court's determination that the proponents could represent the interests of the state in seeing its laws defended to grant them Article III standing. (Neither the California Supreme Court nor the Ninth Circuit addressed the issue of personalized injury.) The Supreme Court, however, essentially has to decide this issue for itself. At oral arguments, there was a clear conflict for the Justices surrounding the competing questions of whether a law enacted by popular vote could be nullified if a governor or attorney general decided not to defend it and also whether any citizen of a state could step up to represent the state's interest.
This means that the Supreme Court could very well decide that the Prop 8 proponents did not have standing to defend the law, meaning that the Court, just as if it had dismissed the case as improvidently granted, would not be able to reach the merits of the law's constitutionality. The difference between these two decisions is that a ruling on standing would vacate the Ninth Circuit's opinion, since the proponents would not have had Article III standing to defend Prop 8 in that court as well. That would mean Judge Vaughn Walker's broad district court ruling that Prop 8 violates the U.S. Constitution on both equal protection and due process grounds would finally be able to go into effect.
There's some uncertainty about exactly what the outcome of such a decision should be, although it's very likely marriage equality would come back to California. Judge Walker ruled that Prop 8 is unconstitutional throughout California and enjoined the governor and attorney general from enforcing it. Technically, however, a district court can only issue a remedy for the specific plaintiffs in the case. This could mean that Walker's ruling would only allow the two same-sex couples who filed the Prop 8 lawsuit to marry, and that it would be up to California's governor and attorney general to decide if they wanted to stop enforcing Prop 8 based on the district court's decision. It's likely there could be more litigation in the California state courts to determine exactly how Judge Walker's ruling should be interpreted and put into effect, so a standing decision could create even more uncertainty.
A decision on the merits
If the Supreme Court decides the Prop 8 case was not improvidently granted and that the proponents do have standing to defend the law, it would then issue a decision on Prop 8's constitutional merits. The Court could limit its ruling to California only, or it could institute marriage equality nationwide. It could also rule that Prop 8 is constitutional and that states can limit marriage to opposite-sex couples. Based on Tuesday's oral arguments, only the first of those three scenarios appears likely. There did not seem to be five votes to explicitly uphold Prop 8, but neither were there five votes for a sweeping ruling. Justice Kennedy, in particular, seemed to hesitate in regard to a broader ruling, saying that he does not believe the social science surrounding marriage equality is conclusive yet or that the Court should dictate marital law to the states. He also seemed skeptical of the Ninth Circuit's California-only ruling. From his apparent distaste for both upholding and invalidating Prop 8, Kennedy appeared eager not to address the constitutional merits of Prop 8.
The DOMA case (U.S. v. Windsor)
A ruling on standing/jurisdiction
In Edie Windsor's case challenging Section 3 of the Defense of Marriage Act, which prohibits duly married same-sex couples from accessing federal marital benefits, there are two related procedural issues that could keep the Court from ruling on the merits of the law. In 2011, the Justice Department, acting on instructions from President Obama and Attorney General Eric Holder, announced it would stop defending DOMA in court and argue instead against the law's constitutionality. The Bipartisan Legal Advisory Group (BLAG), a 5-member body in the House of Representatives made up of the Republican and Democratic party leadership, voted 3-2 on party lines to defend the law.
During Wednesday's arguments, the Justices asked whether BLAG has standing to appear in court in defense of DOMA and whether the Court itself has jurisdiction to hear the appear since the federal government (the defendant in the case) and Edie Windsor (the plaintiff) agree on the law's merits and both want it to be struck down. On the former issue, most of the Justices seemed less than convinced that BLAG should be allowed to join the case as a party, since it is only a small subgroup of one house of Congress and because it falls to the Executive Branch under the U.S. Constitution to execute and defend the nation's laws--or to do neither.
On the issue of the Court's jurisdiction, the Justices asked if the United States could point to any specific injury present in the case that would allow it to seek an appeal of the district court decision. At the same time, the Justices also expressed concern about issuing a ruling that would allow parties to appeal cases in which both sides agree on the fundamental constitutional issues.
As in the Prop 8 case, if the Court were to rule both that BLAG lacks standing to defend DOMA and the federal government cannot appeal a decision that it agrees with, there would be no ruling on DOMA's constitutionality. The Second Circuit's dramatic decision invalidating DOMA would be vacated, and the district court's ruling striking down the law and ordering a tax refund for Edie Windsor would be final. DOMA would still be on the books and it would be up to President Obama to decide whether or not to continue enforcing the law.
A ruling on the merits
Unlike during the Prop 8 oral arguments, Justice Kennedy did appear during Wednesday's hearing to be leaning towards the position that there was a recognizable injury in the DOMA case (since a ruling in Windsor's favor would force the federal government to refund over $363,000 to her) and that the Court could issue a ruling on the merits. There was a clear majority on the Court in favor of invalidating DOMA: the liberal Justices appeared open to striking down the law as a violation of equal protection, while Kennedy and Chief Justice Roberts (and, to an extent, Justice Alito) seemed open to ruling it an unconstitutional intrusion of federal power upon an area of traditional state sovereignty. Between these five to seven Justices, some majority decision against DOMA seems very likely.
A ruling striking down DOMA would only affect Section 3 of the law (since only that section was challenged in court) and would allow married same-sex couples across the country to access federal marital benefits. Of course, Section 2 of the law, which allows states to ignore marriages between same-sex couples obtained in other states, would remain on the books. (It's also likely that even without Section 2, states would be free to continue to ignore same-sex couples' marriage licenses from outside states.) This could very well lead to substantial legal confusion in terms of marital benefits, since a couple who married in Iowa (where marriage equality is legal) but moved to Missouri (where it is not) would possibly be eligible for federal but not state benefits. As always, it would take further litigation to sort through these issues entirely.
The bottom line
To put it simply, there are several combinations of actions that the Supreme Court could take on the Prop 8 and DOMA cases. Absent an invalidation of DOMA and a ruling that extended equal marriage rights to same-sex couples in all 50 states, the post-decision legal terrain will probably look different but nearly as complicated as it is right now. There will undoubtedly be more lawsuits filed pertaining to the intersection of state and federal marital benefits if DOMA is struck down, and there could be further legal fights in California depending on the Court's ruling on Prop 8. And, of course, equal marriage campaigns will continue to take place in state legislatures, at the ballot box, and in the state courts. There is plenty more to come.