A federal court struck down Arizona's ban on abortions after 20 weeks of pregnancy, Tuesday.
The 9th U.S. Circuit Court of Appeals said the law violated a woman's right to terminate a pregnancy before a fetus is able to survive outside of the womb.
A fetus is generally considered "viable" at 24 weeks. Nine other states have bans on abortions starting at 20 weeks, and some even earlier.
Supporters of the ban say the law was meant to protect the mother's health and prevent fetuses from feeling pain.
And lawyers representing Arizona argued that the ban was technically a medical regulation rather than a law because of the stipulations allowing doctors to perform emergency abortions.
"The challenged Arizona statute's medical emergency exception does not transform the law from a prohibition on abortion into a regulation of abortion procedure," Judge Marsha Berzon said. "Allowing a physician to decide if abortion is medically necessary is not the same as allowing a woman to decide whether to carry her own pregnancy to term."
But supporters of the ban said they will not stop fighting.
"Given the compelling and important interest Arizona has in protecting the health and well-being of expectant mothers from the dangers of abortions after 20 weeks and to protect children in the womb from needless and horrific imposition of pain, we will seek review from the United States Supreme Court," Maricopa County attorney Bill Montgomery, who argued before the court in support of the ban, said.
"If the 9th Circuit cannot permit Arizona to act because of Supreme Court precedent, then the Supreme Court must change that precedent," he added.
Republican State Sen. Kimberly Yee, who is 20 weeks pregnant and a sponsor of the legislation, said she "wasn't surprised" by the ruling because of the liberal reputation of the 9th U.S. Circuit Court.
"I'm optimistic that the state will have a compelling argument if we move this before the Supreme Court," Yee said.