PHOENIX (AP) — The family of a little girl who was killed when her mother's car was rear-ended by a Jeep on a Phoenix freeway can sue the SUV's manufacturer for wrongful death because it did not install automatic emergency braking devices that were available as optional equipment, the Arizona Supreme Court ruled Tuesday.

The court rejected arguments from lawyers for Jeep parent company Fiat Chrysler Automobiles US that the National Highway Transportation Safety Administration's decision not to require the devices pre-empted the state lawsuit.

The decision written by Justice Bill Montgomery also overturned a similar 2019 decision that said automakers were immune to such lawsuits because of the federal agency's decision not to require the technology.

The crash on Aug. 15, 2015, killed 4-year-old Vivian Varela, who was riding in the back seat of her mother's Lexus sedan. Melissa Varela was preparing to take an exit from the Loop 101 freeway in north Phoenix when traffic stopped because an emergency vehicle was blocking the off-ramp, according to one of her lawyers, Brent Ghelfi.

A nurse who had just ended her shift at a nearby hospital was also intending to take the exit but did not notice stopped traffic until it was too late. Her Jeep Grand Cherokee slammed into the back of the Lexus, killing Vivian and injuring her mother.

Vivian was the only child of Melissa and her husband, Mitchell, who lived in metro Phoenix at the time but now live in Franklin, Wisconsin.

Ghelfi said the 2014 Jeep could have been equipped with Fiat Chrysler's version of automatic emergency braking but it was only included as an option with a package upgrade that added $10,000 to its price.

"What Chrysler did was they had a safety system that the Insurance Institute of America has studied that says it will prevent 60% of rear end collisions," Ghelfi said. "It's a massive game changer in terms of automobile collisions."

He said automakers have been incredibly slow to adopt the crash-prevention technology while noting how automakers have adopted airbags and other safety features to protect occupants. The item costs automakers about $100.

"And the real tragedy here is they option it," Ghelfi said. "They take a safety feature and they bundle it together with moonroof and leather seats and non-safety features. So you can only get the safety feature if you buy the upgraded trim level."

In a statement, Fiat Chrysler Automobiles extended their sympathies to the Varela family "for their loss and other injuries stemming from this horrific, high-speed collision caused by an inattentive driver."

"While we disagree with the Arizona Supreme Court's ruling on the preemption defense, we look forward to presenting our other defenses to the trial court," the statement said.

The company noted that the Jeep Grand Cherokee involved complied with all applicable federal safety standards and said that while automatic emergency braking, known as AEB, is a promising new technology, it can't prevent all crashes.

"Lawsuits attempting to impose an autonomous feature on all vehicles can inadvertently stymie the development of better versions as technology matures," the company said.

Federal regulators have not mandated the equipment. The Supreme Court's decision noted that the federal safety agency opted to forego imposing a mandate for several reasons, including that it wanted to spur innovation and because automakers were adopting the technology on their own

"To the extent the administrative record reflects a federal policy about AEB technology, it is that the Agency encourages AEB innovation and desires it be deployed more broadly and sooner rather than later," Montgomery wrote.

The case now goes back to a trial court, unless Fiat Chrysler files an appeal with the U.S. Supreme Court. Expert witnesses have been retained and depositions takes, so a trial could happen quickly.

Ghelfi, the Varela's lawyer, called automakers' failure to universally adopt automatic emergency braking "a nationally important and fundamental issue."

He said modeling done by experts determined that if Chrysler's version of emergency braking had been installed on the Jeep, Vivian would not have died.

"It would have automatically braked that car, and this accident would have been a clean miss," Ghelfi said. "At worst it would have been a fender bender, and most likely it would have been a clean miss."