The 9th U.S. Circuit Court of Appeals judges in San Francisco are set to hear arguments Monday in the fight to overturn Arizona's ban on abortions at 20 weeks of pregnancy.

Opponents say the regulation is unconstitutional because it prevents some women from having abortions before viability, the time that a fetus can survive outside the womb, about 23-24 weeks.

On July 30, U.S. District Judge James Teilborg refused to block the ban, saying it's a regulation and not a flat prohibition.

He ruled the law did not block a woman from choosing to have an abortion.

Nine other states also have 20-week abortion bans.

However, Arizona's ban is considered the earliest in the nation because it calculates the starting point of a fetus differently.