Conditionally autonomous cars, where a computer handles most of the driving but a human is expected to sometimes take over, could do more harm than good, and British lawmakers are starting to catch on. The British House of Lords’ Science and Technology Select Committee, released a report on Wednesday into self-driving cars that suggests “level three” autonomous vehicles, could be too risky to even consider for the roads.

“Level 3 autonomy [...] may require CAV [connected and autonomous vehicles] to hand back control of the vehicle to the driver when it is unable to deal with a certain situation,” the report reads. “We received evidence suggesting that handing back in this way to a potentially unprepared driver could be very dangerous.”

The committee heard evidence from Neville Stanton, professor of human factors in transport at the University of Southampton, who said:

As vehicles become fully autonomous, even the most observant human driver’s attention will begin to wane. Their mind will wander … This is particularly true if they are engaging in other activities such as reading, answering emails, engaged in conversations with passengers, watching movies or surfing the internet.

It’s a sentiment backed up by Ford, whose chief engineer of autonomous vehicles told Inverse in a recent interview that the company may skip level three altogether. Jackie DiMarco explained that “level four” autonomy, where the car drives itself unaided through a limited space like a city, could serve as a better goal:

In United States policy making, level three vehicles are classed with higher levels as “highly automated vehicles,” but the National Highway Traffic Safety Administration noted in its federal automated vehicles policy that automakers may need to monitor human awareness as part of their cars’ designs.

Another concern the administration raised is that level three car drivers could lose driving practice, delaying familiarity of a car’s characteristics over time. This, coupled with reduced diligence, could increase the risk from level three cars over time.

That’s about as far as the agency goes. The policy dates back to September, but it’s interesting to note that the British committee, and the automaker industry in general, has struck a far more cautious tone toward level three autonomy. With level four cars expected to hit the streets by 2020, and level two autonomy still reserved for high-end Teslas and the like, it’s possible the industry decides to avoid the hassle and skip level three, rendering the debate moot.

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