An appeal to the Supreme Court on the case is all but guaranteed by the losing side, but it would go first to the 9th Circuit U.S. Court of Appeals in San Francisco, considered the most liberal federal appeals court.

An issue the defendants could use if the law is overturned is what legal standard was applied in the case.

Maria Blanco, the executive director of the Chief Justice Earl Warren Institute on Race, Ethnicity & Diversity at the University of California, Berkeley, said the court right now is looking at this as a rational basis test.

Judges utilize this legal method to examine whether a law is arbitrary or had a reasonable and rational basis for being created. It is most often seen in cases where the plaintiffs claim their equal protection rights under the Constitution were taken away.

"Let's say the plaintiffs survive and win [in this case] and they win on a rational basis, I'm sure the defendants would appeal and say they didn't meet the rational basis test ... or could appeal by saying the court used the wrong standard," she said.