The United States Court of Appeals for the Fifth Circuit this week affirmed a lower court’s ruling that Navistar and its subsidiary IC Bus weren’t liable for the death of a 13-year-old boy who fell out of the back of a school bus in 2016.

Gabriel Miranda Jr. rode with his eighth-grade class aboard the 2010 IC Bus CE-series on Interstate 69 in Texas when he opened the rear emergency exit and fell onto the highway, suffering fatal severe head trauma, according to the case background in the ruling.

Miranda’s family argued, through automotive electronics engineer Rob Berriman, that Navistar should have included an automatic in-motion lock to prevent someone from opening the rear exit at highway speed. However, a federal National Highway Transportation Safety Administration (NHTSA) regulation requiring manual release for emergency exits takes priority, the court found.

The NHTSA reviewed that regulation in 1992 and found that “an important factor in minimizing post-crash injuries and deaths on buses is the speed and ease with which occupants can evacuate the vehicle in an emergency.”

Said the Fifth Circuit in its ruling this week: “In our view, the requirement of a simple, manual release mechanism is consistent with these concerns because of the ‘speed and ease’ it allows a student to operate an emergency exit and escape from the school bus. In contrast, an automatic speed lock carries a risk of mechanical failure, consequently increasing the risk that students will be trapped aboard school buses in emergencies.”

Officials at Navistar declined comment about the ruling when reached by School Bus Fleet.