A significant barrier to Google’s plan to put driverless cars on the roads without steering wheels or brakes has been removed, after a US transport regulator indicated that a robot could meet the legal definition of a driver.

In a letter to Chris Urmson, the director of Google’s self-driving car project, the National Highway Traffic Safety Administration said it agreed with the Alphabet-owned company’s proposed interpretations of Federal Motor Vehicle Safety Standards, which every car must pass before being allowed on the roads.

Google maintains that cars will be safer when humans have no control or ability to intervene in driving at all, instead relying solely on an artificial intelligence system that makes potentially life-and-death decisions based on data from an array of sensors, maps and cameras.

This approach is more extreme than many carmakers who advocate a more gradual progression towards autonomous driving that will still require driver control for many years to come.

Last year, the idea hit a potential roadblock when the California Department of Motor Vehicles said that any autonomous cars being tested on the state’s roads must have a steering wheel and pedals. Google has argued against that proposal and received a boost last month when the US secretary of transportation, Anthony Foxx, said he would put forward new national rules for “fully autonomous vehicles” in the coming months.