Two lawyers involved in California’s landmark Proposition 8 case on Sunday predicted that same-sex marriage would soon be legal nationwide.

“This has to do with equal rights,” David Boies told host Chuck Todd on NBC’s “Meet the Press.”“As long as you don’t discriminate against anyone based on race, gender, religion, etc., everyone is equal under the law,” he added.“We don’t take away the rights of the individuals, put them in a box and say that they’re less equal,” Ted Olsen continued. “We don’t do that in this country.”“The overwhelming evidence of the case we tried is that sexual orientation is an immutable part of a person’s characteristics,” Olsen added of their work on Proposition 8 over same-sex marriage in 2008.The Supreme Court will begin hearing oral arguments on same-sex marriage Tuesday.Both men predicted on Sunday that justices will eventually rule in favor of same-sex marriage. A verdict is due in June.“It’s now overwhelmingly taken over the country,” Boies said of support for gay marriage.“You can’t deny a loving couple their rights,” he added.Boies said he hoped the justices’ decision was definitive. The case is too important to Americans, he argued, for a sharp divide in their ruling.“I think that civil rights cases should be decided 9-0, 8-1,” he said, hoping for the court’s overwhelming approval on such cases.“The more justices that sign on, the better,” Boies added.The two attorneys rose to prominence after California passed a ban on same-sex marriages in 2008.The Supreme Court ruled in a 2010 decision that the law, known as Proposition 8, was unconstitutional.Many opponents argue same-sex marriage is an issue best decided at the state level.