The first federal trial to determine if the U.S. Constitution prohibits states from outlawing same-sex marriage gets under way Monday, and the two gay couples on whose behalf the case was brought will be among the first witnesses.

The proceedings, which are expected to last two to three weeks, involve a challenge to Proposition 8, the gay marriage ban approved by California voters in November 2008.

Regardless of the outcome, the case is likely to be appealed to the U.S. Supreme Court, where it ultimately could become a landmark that determines if gay Americans have the right to marry.

The judge who will render a decision, Chief U.S. District Judge Vaughn R. Walker, has asked lawyers arguing for and against the ban to present the facts underlying much of the political rhetoric surrounding same-sex marriage. Among the questions Walker plans to entertain are whether sexual orientation can be changed, how legalizing gay marriage affects traditional marriages and the effect on children of being raised by two mothers or two fathers.

“The case is intriguing, exciting and potentially very significant because it addresses multiple important questions that, surprisingly to many, remain open in federal law,” said Jennifer Pizer, marriage director for the gay law advocacy group Lambda Legal. “Can the state reserve the esteemed language and status of marriage just for heterosexual couples, and relegate same-sex couples to a lesser status? Are there any adequate public interests to justify reimposing such a caste system for gay people, especially by a majority vote to take a cherished right from a historically mistreated minority?”

Read the rest of Lisa Leff’s AP article here.