A bill in Congress would require alerts for drivers if children are still in cars that have been turned off.

A proposed new law that would require carmakers to build alarms for back seats is being pushed by child advocates who say it will prevent kids from dying in hot cars.

The law also would streamline the criminal process against caregivers who cause the deaths – cases that can be inconsistent but often heavier-handed against mothers.

The latest deaths came in Arizona on triple-digit degree days over the weekend, with two baby boys found forgotten in vehicles in separate incidents.

More than two dozen child and road safety groups are backing the Senate bill introduced last week aimed at preventing those kinds of deaths by requiring cars to be equipped with technology that can alert drivers if a child is left in the back seat once the vehicle is turned off.

It could be a motion sensor that detects a baby left in a rear-facing car seat and then alerts the driver, in a similar way that reminders about tire pressure, open doors and seat belts now are standard in cars.

Police say 1-year-old Josiah Riggins was in the car for hours Saturday, found dead only after his father drove round-trip twice between their suburban home and a Phoenix church to drop off the mother and a sibling.

Zane Endress, who was 7 months old, died Friday in Phoenix after being left in the car in the driveway at home, as his usual daycare drop-off routine was lost by his grandparents.

“A simple sensor could save the lives of dozens of children killed tragically in overheated cars each year, and our bill would ensure such technology is available in every car sold in the United States,” bill sponsor Sen. Richard Blumenthal, a Democrat from Connecticut, said in a statement.

No charges have been filed against the caregivers in either Arizona case, as police say investigations are underway.

Kids and Cars, which has tracked more than 800 children who have died in this way since 1990, said criminal cases vary greatly, even when circumstances are identical.

The nonprofit’s analysis shows charges are filed about half of the time, though very rarely are the parents found guilty. There is also a noted gender bias: Mothers are more often charged than fathers, and among the convicted, women get longer prison sentences than men, the study found. “I think society feels sort of like moms are in charge, and they’re supposed to do everything,” said Janette Fennell of Kids and Cars.