The National Highway Traffic Safety Administration issued a long-awaited final rule Monday requiring vehicles to be equipped with what regulators call rear visibility technology.

The technology is expected to significantly reduce fatalities and serious injuries caused by a driver backing over a person, particularly a young child, who cannot be seen behind a vehicle. The final rule requires all new vehicles less than 10,000 pounds gross vehicle weight, including passenger vehicles, buses and trucks, to have this technology in place by May 2018.

In 2008, Congress passed a law requiring the Transportation Department to issue a federal safety standard on the issue by 2011. The rule was delayed several times, spurring a coalition of safety advocates to sue the agency over the delays.

A federal appeals court was scheduled to hear arguments today on whether to order the Transportation Department to issue the standard.

The final rule amends the current federal motor vehicle standard by expanding the area behind a vehicle that must be visible to the driver when the vehicle is shifted into reverse. That field of view must include a 10-foot-by-20-foot zone directly behind the vehicle. The system used must meet other requirements as well, including the size of the image displayed for the driver.

According to the safety regulators, automakers will use rearview video systems and in-vehicle displays to meet the requirements in the near term.

NHTSA estimates that, on average, 210 fatalities and 15,000 injuries each year were caused by these back-overs, and that children younger than 5 account for 31 percent of back-over fatalities each year. The agency said it took extra time on the regulation to ensure that it was flexible and achievable.

According to a statement issued Monday by the Alliance of Automobile Manufacturers, automakers currently provide rearview cameras as either a standard or optional feature on two-thirds of the nation’s 50 top-selling vehicles.

The new rule satisfies the mandate of the Cameron Gulbransen Kids Transportation Safety Act of 2007, which was named for a 2-year-old boy who was run over and killed by his father, Dr. Greg Gulbransen, in his driveway in 2002.

In a statement issued Monday by Public Citizen, a consumer advocacy group, Gulbransen said: “It’s been a long fight, and this rule took too long, but we’re thrilled this day has finally come. It’s a bittersweet day, because this rule should have been in place three years ago at the latest. But this rule will save lives.”