The U.S. Supreme Court begins hearing oral arguments in two same-sex marriage cases this week, the outcome of which could have a profound impact on how America defines marriage and family, CNN reports. On Tuesday, the justices will hear a challenge to California's Proposition 8, the 2008 voter-approved ballot measure which defines marriage as between a man and a woman and effectively bans gay marriage. California voters approved it as a ballot initiative by 52 to 48 percent in November 2008 less than six months after the state Supreme Court ruled marriage was a fundamental right that must be extended to same-sex couples. The overriding legal question in the case is whether the 14th Amendment's guarantee of "equal protection" prevents states from defining marriage as California has. The Obama administration has formally expressed support for same-sex marriage in California, weighing in on the case in a brief last month. In a separate argument on Wednesday, the Supreme Court will take on the federal Defense of Marriage Act (DOMA), a 1996 law defining marriage for federal purposes as between a man and a woman. As the split 5-4 conservative-liberal bench -- which has the option of ruling broadly or narrowly -- is poised to perhaps offer the final word on the issue, supporters of traditional marriage worry that legalizing same-sex marriage could have serious consequences. It could be the first step to redefining marriage altogether, possibly leading to polygamy or even group marriages -- ideas openly supported by some advocates of gay marriage. It could also eventually hurt religious freedom in America as churches, religious organizations and even businesses would have to support whatever the government defines as a marriage or risk facing government action.