A patchwork of state laws governing the operation of self-driving cars threatens to stall their development, supporters told lawmakers as U.S. senators began consideration of a national standard for robotic vehicles.

“It’s absolutely critical that we have uniform rules across the country,” Senator Gary Peters, a Michigan Democrat, said in an interview. “These are vehicles that will be on interstate highways and going across state lines. If you have a patchwork of state regulations, it will slow down the process, add confusion and ultimately, I don’t think will add to safety or the advancement of these technologies.”

By taking the wheel from error-prone humans, driverless cars are expected to dramatically reduce road deaths, which rose to 38,300 in the U.S. last year from 32,675 in 2014, Peters said. In a hearing today before the Senate Commerce Committee, officials from Google, General Motors Co. and other companies developing driverless cars said they need national standards to deploy robot cars quickly and safely. And they found a receptive audience among the senators on the committee.

“The greatest obstacle to these vehicles may be a patchwork of state and local laws,” said Senator John Thune of South Dakota, the Republican chairman of the committee. “We must be careful not to stymie innovation through a lack of imagination.”

Mobility Options

Safety will improve under automated-vehicle technology, Thune said. The cars don’t get tired or distracted. Older and disabled people will have more options for mobility, he said.

Deaths are increasing on American highways due partly to more people driving in a growing economy with cheap gas. Peters also blamed an increase in distracted driving.

“As people are texting and on cell phones, there are a lot of distractions,” Peters said. “This should highlight why we have to incorporate these safety features and have autonomous vehicles.”

Semi-autonomous features, such as automatic braking and steering, are already making roads safer by helping prevent collisions, Peters said.

“The wonderful thing about these technologies is that they do not get distracted,” he said. “They are not texting. They’re not driving down the road with a cheeseburger that falls in their lap while they’re talking on the phone. They’re always on guard.”

Google Executive

At the hearing, Chris Urmson, director of self-driving cars at Google, testified that over the past two years 23 states have introduced 53 pieces of legislation that affect automated vehicles. Five states have passed laws, all with different definitions, licensing structures and sets of expectations for what manufacturers should be doing.

“If every state is left to go its own way without a unified approach, operating self-driving cars across state boundaries would be an unworkable situation,” Urmson said. Different state laws will “significantly hinder safety innovation, interstate commerce, national competitiveness, and the eventual deployment of autonomous vehicles.”

Google has pushed the envelope of self-driving technology by deploying test cars without a steering wheel or a brake pedal. Those designs conflict with existing motor-vehicle regulations, the National Highway Traffic Safety Administration said.

Another witness, Mary Cummings of Duke University in Durham, North Carolina, cautioned lawmakers that a lot more research, testing and leadership from the federal government is needed before control can be handed over to robot drivers.

“While I enthusiastically support the research, development, and testing of self-­driving cars, as human limitations and the propensity for distraction are real threats on the road,” Cummings said in written testimony. “I am decidedly less optimistic about what I perceive to be a rush to field systems that are absolutely not ready for widespread deployment, and certainly not ready for humans to be completely taken out of the driver’s seat.”