Marriage equality for same-sex couples will be front and center this Monday, December 6, as the U.S. Court of Appeals for the Ninth Circuit in San Francisco hears oral argument in the appeal of the federal District Court ruling striking down California’s infamous Proposition 8, a ballot measure that amended the state Constitution to prohibit same-sex couples from marrying. The argument will be broadcast live on C-SPAN starting at 1pm Eastern/10am Pacific. My organization, Constitutional Accountability Center (CAC), has filed a friend of the court brief in this case in support of the ruling invalidating Prop 8, and my colleague Elizabeth Wydra (CAC’s Chief Counsel) and I will be “live blogging” the argument on Huffington Post as soon as things get underway. Whether or not you can get to a TV, we hope you’ll join us on Monday, as we discuss the proceedings, live. For now, here’s a short preview of the case and what to expect during the argument.

The case itself, Perry v. Schwarzenegger, was brought by interesting legal bedfellows – Ted Olson and David Boies – who famously squared off against each other in Bush v. Gore and have since joined forces to represent the same-sex couples who have challenged Prop 8. (We expect that both Olson and Boies – two of the country’s best appellate advocates — will be sharing argument time on Monday.) For gay men and lesbians, the stakes in Perry could not be higher. Unlike other marriage cases that have been decided under state Constitutions and thus did not present issues of federal law that could be heard by the U.S. Supreme Court, at issue in Perry is whether the denial of marriage equality violates the U.S. Constitution. In August, District Judge Vaughn Walker, after a full trial on the merits, held that it does, and struck down Prop 8 as a violation of the equal protection and due process rights of same-sex couples under the Constitution’s 14th Amendment. This means that if the Ninth Circuit rules on this issue one way or the other, the case could be headed to the Supreme Court.

But the Ninth Circuit may not even reach the merits, given a legal doctrine known as “standing,” which in the context of this appeal would typically require those seeking to overturn Judge Walker’s ruling to show that they would be harmed by it. The state of California declined to defend Prop 8, and its proponents intervened in the case in order to provide a defense. Thus, as a threshold matter, the Ninth Circuit will need to decide whether the sponsors of a ballot measure have the requisite “standing” to pursue an appeal of a ruling holding that the measure is unconstitutional.

The Court of Appeals has already indicated it intends to give lengthy consideration on Monday to all of these issues. In fact, before you tune in, be sure you’ve had a good meal. As oral arguments go, this one will be a marathon: the court has allotted a full two hours to hear the case, more than double the Ninth Circuit’s usual argument time of 20 to 40 minutes per case. The first hour will be devoted to the issue of “standing,” and the second to the merits of Judge Walker’s ruling. Undoubtedly, unless you are a legal geek, you may not find the first hour of Monday’s oral argument as fascinating as the second, but Elizabeth and I will do our best to liven it up.

Once we get to the second hour, expect to hear Prop 8 ‘s supporters use the word “procreation” repeatedly – their main argument is that prohibiting same-sex couples from marrying is rationally related to the state’s interest in “responsible procreation and childrearing.” (If that makes no sense to you, you aren’t alone; it made none to Judge Walker.) For their part, Prop 8’s opponents will be focused on “equality,” and the fact that Prop 8 discriminatorily denies gay men and lesbians the right to marry, in violation of the 14th Amendment. Indeed, as we demonstrated in CAC’s amicus brief, the Framers of the 14th Amendment considered the right to marry the person of one’s choice to be a fundamental right, fully protected by that Amendment’s Equal Protection Clause–a right the Supreme Court finally vindicated for interracial couples in 1967, in the landmark case Loving v. Virginia.

With marriage equality hanging in the balance for same-sex couples, don’t miss the chance to witness history in the making. We hope to see you  on Huffington Post Monday at 1pm Eastern/10am Pacific!