Arizona Senate Pres. Warren Petersen (R-12) and House Speaker Steve Montenegro (R-29) have officially intervened in a lawsuit related to last election’s Proposition 139, more commonly known as the “Right to Abortion Initiative.” The case, entitled Isaacson v. Arizona, was filed in Maricopa County Superior Court on May 22, 2025, by the plaintiff, Dr. Paul A. Isaacson.

Isaacson and a group of healthcare providers seek to overturn several Arizona statutes protecting unborn children and their pregnant mothers. Some of the rules they want removed include bans at specific gestational ages, restrictions on medication abortion, and requirements for multiple clinic visits. Many on the right see this case as a challenge to an unborn child’s right to life.

Petersen said that he and Montenegro had been expecting challenges to the state’s current laws since Proposition 139 passed last November, enshrining in Arizona’s constitution an individual’s fundamental right to abortion.

One of those laws is Arizona’s prohibition on aborting babies solely for birth defects, like a cleft palate or lip, clubfoot, Down syndrome, or spina bifida. The primary plaintiff in Isaacson, Dr. Paul A. Isaacson, has been performing abortions in Arizona for nearly three decades and is the co-owner of Family Planning Associates Medical Group (FPA) in Phoenix. His clinic performs abortions for $700 to $2,500 each and up to 24 weeks, past the point of viability and when the fetus is 12 inches long, weighing over one pound, capable of responding to light and possessing fully developed inner ears, among other accomplishments. FPA performed 2,644 abortions according to the 2023 Arizona Abortion Report, approximately 21% of all abortions in the state.

“Medical advances are making some fetal structural issues treatable in the fetal and neonatal periods, but there is a wide range of outcomes even where attempted treatment is possible,” the lawsuit read. “Some are invariably incompatible with sustained life, but even for those, there may be considerable uncertainty as to how long a child born with the anomaly may live.”

Petersen, who is running against Mayes for the Attorney General position in 2026, described the attempt to overturn laws protecting unborn Arizonans with special needs “as discriminatory, heinous and troubling.” Montenegro, meanwhile, said he intends to present a vigorous defense to demonstrate the commonsense necessity of Arizona’s current abortion laws. The legislative leaders have hired outside counsel to prepare a defense and will eventually file a response, though the entire case could take years to resolve.

“Arizona’s laws are designed to protect the health and safety of pregnant women and their unborn children, and to prevent unlawful discrimination. I was proud to intervene in this lawsuit on behalf of the Arizona House of Representatives to vigorously defend Arizona’s pro-life laws,” Montenegro said. “House Republicans are firmly committed to applying the law with care and prudence to safeguard all human life while upholding the dignity of women at every stage of pregnancy.”

“The Senate President and Speaker both have the final say on whether they intervene on a case. Either chamber may go it alone, but we usually go together,” said Petersen, who is a Gilbert resident. “We’re defending laws that our current AG [Democrat Kris Mayes] refuses to defend.”

The outcome of the Isaacson case could have a dramatic impact on Arizona’s abortion laws. The Globe will update as information becomes available.