Two systems are used to produce A.D.B. headlamps. Matrix headlights, such as those from Audi, use multiple LEDs that can be turned on and off in different groups to alter the beam pattern. Other systems use a combination of projector lamps and shades that can cover parts of the beam.

In development are pixel systems that can trim the light point by point, and a laser system that uses micro-mirrors.

Whichever technology is used, the goal is to shape the light, throwing it a maximum distance while keeping it out of the eyes of oncoming drivers, whether they’re in a tractor-trailer or on a motorcycle. Doing so requires sophisticated software, sensors and cameras capable of quickly and accurately detecting oncoming traffic. Much of that gear is already in modern vehicles.

The initial specifications proposed by the National Highway Traffic Safety Administration differ from those that have been in use for years in Europe and elsewhere. In other markets, A.D.B. high-beam lights can put out twice the light intensity currently allowed for high beams in the United States. And the agency wants A.D.B. headlights to also put out a minimum amount of light everywhere, even in the shadow areas where an oncoming driver’s eyes might be.

Neither idea is a good one, Mr. Stern said. He pointed out that as long as the light didn’t dazzle an oncoming driver, brightness could be safely increased to European standards. And projecting a minimum amount of light in every area could still blind a driver at certain angles.

“It does not make sense to have a high-beam limit with A.D.B. lamps, as there won’t be any glare,” said Matthew Brumbelow, senior research engineer at the Insurance Institute for Highway Safety. He said his organization would ask the federal highway agency to allow A.D.B. high beams to be brighter.

In anticipation that these headlamps will be approved, Audi already sells vehicles in the United States with “matrix-design” LED lamps that need only a software upgrade to turn on the adaptive beam, Mr. Berlitz said. If the American standards differ from Europe’s, new software will have to be written, he said.