The first federal trial to determine if the U.S. Constitution prohibits states from outlawing gay marriage began in San Francisco this morning.

The case, Perry vs. Schwarzenegger, is expected to become a landmark case that eventually will be decided by the U.S. Supreme Court. Both sides have hired leading legal advocates with lots of experience before the high court.

LAist has compiled an excellent Q&A guide that not only explains the case but also give us some historical context. Below is an excerpt from LAist’s [Guide: The Federal Prop 8 Trial](http://laist.com/2010/01/11/quick_guide_the_federal_prop_8_tria.php):

What is Prop 8?
Prop 8 was the California ballot initiative in November of 2008 that banned same-sex marriage, subsequent to a state Supreme Court ruling legalizing the marriages earlier that year on May 15th. One month later on June 16th, the first of 18,000 gay couples were able to tie the knot.

What is today’s case about?
The federal trial is about the unconstitutionality of Proposition 8, which in part takes into account how it violates the Equal Protection Clause of the 14th amendment, which says that "no State shall deprive any person of life, liberty or property, without due process of law; nor deny to any person the equal protection of the laws."

"The defendants have the burden of demonstrating that Prop. 8 is narrowly drawn to serve a compelling government interest," explained a news release from the American Foundation for Equal Rights, which assembled the legal team to fight the Prop.

In addition to violating the 14th Amendment, the suit alleges that Prop 8:
• Violates the Due Process Clause by impinging on fundamental liberties.
• Singles out gays and lesbians for a disfavored legal status, thereby creating a category of "second-class citizens."
• Discriminates on the basis of gender.
• Discriminates on the basis of sexual orientation.

To learn more about who the defendants and the legal players are visit LAist.