The Association for Computing Machinery shed doubt on the practicality of fully automated vehicles in a recent informational bulletin.

It said it’s unclear that automatic vehicles will ever reach the point of operating safely without direct driver engagement except in limited circumstances, such as controlled conditions on particular roads.

“Many more miles of AV driving are required to establish fully automated vehicles as safe enough to deploy on public roadways,” it said in the bulletin.

“The goal of many automated vehicle proponents is the routine and widespread use of fully automated vehicles on all public roads. For now, however, the feasibility of reaching that goal is uncertain as experimental automated vehicles have caused, and continue to cause, serious injuries and fatalities to public road users, as well as other problems.”

The association, which refers to itself as the world’s largest educational and scientific computing society, offered the perspective as informational rather than aimed at policy advocacy.

Full automation has been controversial, and accidents involving automated taxis have spurred some governmental curbs on their use, including in California, which suspended the deployment and permitting of General Motors’ Cruise driverless taxis in October. Many consumers have also expressed wariness about driverless cars.