PASADENA >> In the next six to eight years, self-driving vehicles may become a reality. And with computers behind the wheel instead of humans, traffic fatalities could sharply decrease, a panel of scientists speaking at a roundtable at Caltech Wednesday night said.

But what happens after a mass adoption of self-driving vehicles remains a ball of confusion swirling around legal issues, ethics, liability, government regulations and social acceptance.

Some on the panel raised questions about those issues, while sometimes leaving the audience of about 200 at the science-based university’s Lees-Kubota Lecture Hall searching for answers.

“The technical problems will be mostly solved in the next couple of years. The bigger issue is how do we deal with liability,” said Paul Lienert, who covers the automotive industry for Reuters and has a doctoral degree in business with an emphasis on electric vehicles.

Pietro Perona, a Caltech professor of electrical engineering, presented the following scenario: A car driven by a human runs a red light heading straight for the autonomous vehicle. Since it knows how to avoid collisions, the autonomous car swerves onto the sidewalk, avoiding the crash. But in the process the vehicle runs over a little boy.

If statistics show only a few accidents with autonomous cars, will the public accept some traffic fatalities? And if not, will people blame the car company and sue?

“How do we trust that vehicle?” Perona asked, saying in the same way, he trusts humans, like his sister, to drive him around. “It will be a statistical decision to let this vehicle loose.”

Richard Murray, a professor of control, dynamical systems and bioengineering, said insurance companies and the courts will have to decide how to navigate the blame game when no one is in the car.

“Society will have to decide about machines that kill someone just as they have about people who kill someone,” Murray said. “Is the autonomous car going to be given the same rights as humans and we say ‘accidents happen?’ Or should the engineers have known better?”

Murray elaborated, saying if a person steps in front of fast-moving autonomous car and gets killed, is that the human’s fault or the car’s?

Perona said part of the solution is integrating driverless cars into the social rules of the road. Today, companies working on self-driving cars such as Tesla and Google program them to keep a safe space from the next car. But when merging onto a freeway, often there is no safe space.

So, human drivers inch their way into the flow of traffic, often receiving a wave or nod, he said.

“These (self-driving vehicles) view oncoming traffic as obstacles. But we use our body language when we drive; we communicate with other drivers so there’s cooperation. These vehicles will have to be able to interact socially with other entities,” Perona said.

Like the race to create the personal computer in the 1980s, today companies are pouring billions into building a marketable self-driving car, said Evangelos Simoudis, a venture capitalist who moderated the panel discussion. Simoudis said 1,000 companies are investing in software and other components of self-driving cars, as well as Tesla, Google, Ford, General Motors, Volvo and Honda.

Mory Gharib, a professor of aeronautics and bioinspired engineering, said such cars will be built within the next five years but making them work in cities is the trick. “The problem is, what happens when we put so many of these driverless cars on the road. How do they follow the rules?”

Ridesharing companies such as Uber and Lyft are investing heavily, as are trucking companies, he said. The first use will be for commercial applications, such as ridesharing, truck driving fleets and vanpools.

Honda has signed an agreement to work on self-driving cars with Waymo, a subsidiary of Google working on the technology. Honda is testing a self-driving Acura RLX at a Naval base in Concord, in the East Bay.

“Some automakers are talking about vehicles without steering wheels or gas pedals. That is not our vision,” said Marcos Frommer, Honda spokesperson. “We want to offer that as a choice or an option. A driver can switch it to autonomous mode.”

While mapping technology is much more precise than even Google Earth, the self-driving car will need to be programed to read any scenario and react accordingly. That may still be five to eight years away, said the panelists.

“It will happen. The question is how soon will it happen?” said Lienert.