American regulators are on track to begin testing camera systems as replacements for traditional exterior mirrors, potentially clearing a road block standing in the way of both automotive design and innovation in the United States.

In a request for comment filed Tuesday, the National Highway Traffic Safety Administration (NHTSA) announced it is going to conduct a study to evaluate the efficacy of cameras as replacements for outside rearview mirrors. The first round will focus on such systems being employed in light vehicles, with a follow-up planned to test the same technology in heavy trucks. 

NHTSA has been collecting data on side-view and rearview mirror replacement technology for years. A trade organization representing some of the world's largest automakers petitioned the agency to allow for the use of cameras in U.S.-bound vehicles in 2014. The petitions are still pending. Meanwhile, manufacturers have begun selling vehicles with cameras replacing side mirrors overseas since 2018. Lexus sells its ES sedan with side-mirror cameras in Japan; Audi's E-tron is sold this way in Europe

General Motors, Nissan, and Infiniti have implemented rear camera mirrors that use cameras to replace the view shown on interior rearview mirrors, but no automaker has been allowed to use camera views instead of side-view mirrors.

For testing purposes, NHTSA will employ both production-spec vehicles sold overseas and retrofitted U.S.-market vehicles. For the light-vehicle testing portion, at least two of the test vehicles will be equipped with both physical mirrors and camera systems; others will have only cameras. Heavy vehicle testing procedures have not been finalized. 

"The safety of passive visibility-related technologies depends on both the performance of the systems and on drivers' ability to effectively and comfortably use the systems," the agency said in its request. "This work seeks to examine and compare drivers' eye glance behavior and aspects of driving behavior and lane-change maneuver execution for traditional mirrors and camera-based systems intended to replace outside rearview mirrors."

This is only the latest example of the United States being behind the curve when it comes to automotive safety systems innovation. For years, European automakers wanted to introduce high-precision adaptive headlight systems to the U.S. market, but were unable to thanks to archaic regulations that prohibited their implementation. It was only as recently as 2018 that U.S. regulators began paving the way for these "matrix" style headlights to cross the pond.