The infrastructure bill signed into law by President Joe Biden on Monday includes more than just funding for roads and bridges. It also updates regulations to finally bring adaptive headlights to the U.S.

Adaptive headlights, also known as matrix headlights, consist of numerous small LED elements and mirrors that can control a light beam in complex ways. This allows the lights to be more precisely aimed, illuminating what the driver needs to see without blinding other motorists.

This goes a step beyond current automatic high beams, which simply shut off the high beam when an oncoming car approaches. Adaptive headlights can shut off the lighting elements facing the oncoming car, while keeping the rest of the road fully lit.

2019 Porsche Cayenne LED matrix headlights

2019 Porsche Cayenne LED matrix headlights

It's this feature that caused a problem for U.S. regulators. A rule dating back to 1967 requires headlights to have separate high-beam and low-beam elements. Because adaptive headlights use the same lighting elements for everything, they're not legal. The National Highway Traffic Safety Administration (NHTSA) first proposed a change to this rule in 2018, saying adaptive headlights had the potential to reduce crashes.

Getting adaptive headlights into U.S.-market vehicles will take some time, however. The law creates a definition of adaptive headlights, and states that a final ruling on amending the original safety standard to include them should take place within two years.

A handful of vehicles sold in the U.S., such as the Mercedes-Benz S-Class and Audi E-Tron, are sold with adaptive headlights in other markets. The new infrastructure law means that technology could be enabled here as well, and perhaps added to less-expensive vehicles, as is the case in other parts of the world.