NEW YORK (NYTIMES) - After 18-year-old Liza Hankins was thrown through the closed sunroof of her sport utility vehicle during a crash and paralysed, her family sued the truck's maker, claiming it had failed to live up to its safety responsibilities.

The carmaker, Ford, won the case after it pointed out that no government regulations required a sunroof - even a closed one - to keep someone inside a vehicle in a crash.

Today, more than a dozen years after Ms Hankins' crash, there are still no government regulations meant to prevent the hundreds of sunroof ejections that happen every year - even as more buyers are ticking the box for the sunroof option and more carmakers are stretching the size of the glass overhead with larger, panoramic sunroofs.

Some carmakers have already taken steps to make sunroofs safer by using laminated safety glass, while gadgets now in the works could help limit sunroof ejections during rollovers. And a new test created by researchers at the National Highway Traffic Safety Administration (NHTSA) could mean the federal government is laying the groundwork for regulations governing sunroofs.

"We know that there are fatalities and injuries," said Ms Cathy Chase, president of Advocates for Highway and Auto Safety. "And it is a solvable problem."

With sunroofs becoming increasingly popular, consumer advocates worry that the danger will grow.

About 7 million, or 40 per cent, of the 2017 model year cars and light trucks sold in the United States came with a sunroof, compared with 33 per cent for the 2011 model year, according to WardsAuto, a trade publication.

Crash data is not as up-to-date, but it is still troubling. About 300 people were killed and about 1,400 injured every year from 1997-2008 when they were thrown out of sunroofs, whether open or closed, the NHTSA said in 2011.

In 2016, the agency did a more limited study of ejections through closed sunroofs only: Between 2002 and 2012, about 230 people were killed and 500 injured each year.

In a statement, the agency said it was "actively looking into this issue and continues to analyse information related to the structural integrity of sunroofs". The agency also said it was "evaluating factors that reduce passenger ejection".

Federal regulators should update their data and take a serious look at sunroof standards, said Mr Jason Levine, the executive director of the Centre for Auto Safety.

"Sunroofs are getting bigger, and so that raises questions that perhaps those numbers are larger," Mr Levine said.

Ms Hankins is among those whose lives were forever changed.

The sunroof in her 2000 Ford Expedition was fun when she first got the vehicle, but the novelty wore off and she usually kept it closed - just as it was when she crashed on the way to work in Yazoo City, Mississippi, in 2005.

"I didn't think I would ever be thrown out of it," she said in a telephone interview.

Ms Hankins has no memory of the crash, but the evidence showed that the truck rolled over, the glass panel of the sunroof popped out and she was thrown through the opening.

"It put me in a wheelchair. It scarred my face really badly," she said.

In the suit against Ford, Ms Hankins' lawyers argued that the carmaker should have used laminated safety glass, the kind used in windshields, and more securely anchored the panel. The lawyers said Ford had known for decades that laminated glass - which uses a layer of plastic film between two layers of glass - was safer, but used less-expensive tempered glass.

The carmaker acknowledged that tempered glass, which is used in side windows, was less expensive. However, it said serious brain and neck injuries could occur when heads hit laminated glass, a danger it concluded was a greater threat to belted occupants than ejection.

Ford asserted that Ms Hankins had not been wearing a seat belt - a suggestion she denied

The NHTSA considered regulating sunroof safety in 2011 when it established rules to prevent side-window ejections but ultimately opted against doing so.

To comply with the side-window rules, carmakers usually rely on curtain air bags that cover the windows.

The agency noted that only 3 per cent of the 10,000 ejection deaths each year from 1997-2008 involved sunroofs. That contrasted with 62 per cent through side windows.

The agency's decision dismayed safety advocates, who said it had ignored a 2005 congressional mandate to reduce the danger of being thrown from a vehicle.

At the time, the agency said that it was in compliance with the mandate and that it was "not reasonable" to adopt a sunroof standard. One major impediment: It did not have a test to measure sunroof safety.

Now, there may be one.

Last year (2017), three NHTSA researchers announced that they had developed "a viable performance test" using a ram to push up and gauge the strength and anchoring of laminated glass in a sunroof.

Mr David Friedman, a former top official at the agency who oversees automotive issues for Consumers Union, said it appeared that the test had been developed with the idea of exploring a new regulation. "I'd argue it should be on the list," he said.

Although research shows that wearing a seat belt greatly reduces the chances of being completely thrown out a sunroof, a partial ejection is still possible in a particularly violent crash, said Mr Stephen Batzer, a forensic engineering consultant from Michigan and a court-recognised expert in car crash safety. If federal regulators decide to explore a sunroof regulation, they will most likely consider mandating the use of laminated glass, Mr Batzer said.

Some carmakers already use laminated glass for sunroofs. Volvo favours it.

"From a safety perspective, the most important aspect of the roof being laminated is to ensure that the occupant stays in the compartment in case of a rollover," Mr Russell Datz, a Volvo spokesman, said in an e-mail.

And Ford - which in Ms Hankins' lawsuit warned that laminated glass sunroofs could be dangerous - now uses it in some of its sunroofs "depending on engineering requirements", said a company spokesman Elizabeth Weigandt. She declined to detail the models or requirements.

An auto-industry supplier in South Korea will soon offer what it says is a better safety option. Hyundai Mobis, which supplies parts to carmakers including Hyundai and Kia, has developed what it believes is the first sunroof air bag.

An air bag would provide protection even when the sunroof was open, said Mr Choon Kee Hwang, a spokesman for the company. He said it could appear on new vehicles in a year or two.