People riding in self-driving cars that crash could find themselves unable to hold the manufacturer accountable if legislation currently pending on Capitol Hill is passed, consumer advocates warn.

They caution that the legislation under consideration in the Senate benefits big tech and car companies at the expense of average Americans.

Legislators have pushed to clear the way for self-driving vehicles. The House unanimously passed a related bill in September. But critics warn that autonomous vehicles won't be perfect, and could have defects that lead to bad crashes. Like all computer systems, they will be vulnerable to hacking.

Among other potential problems, research has shown, for instance, that placing stickers on a stop sign can cause a self-driving car to misinterpret it as a speed limit sign, which could trigger a crash at an intersection.

Critics are concerned that the bill, known as the AV Start Act, does not prohibit forced arbitration between autonomous vehicle manufacturers and consumers. A person badly injured while riding in a self-driving car would not be able to take part in a class action lawsuit, or sue the maker of the technology. Instead, disputes would be settled in arbitration. Experts say arbitration shifts the balance of power in the favor of big businesses, because they generally hire the arbitrator and will be its repeat customer.

Arbitration proceedings are also private, so use of them would mean the public is more likely to be kept in the dark about flaws in self-driving vehicles.

"The nightmare scenario is that someone is hurt because of a defect and it's dealt with through a confidential arbitration proceeding that nobody knows about, and then more people are hurt because no one found out about it," Ed Walters, who teaches robotics law at Georgetown Law and Cornell Tech, told CNN. "Congress could stick up for the right to sue by prohibiting these kind of clauses, but so far they haven't."

Wednesday afternoon, five Democratic Senators released a letter calling for changes in the bill in which they outlined concerns including the bill potentially pre-empting state and local traffic laws. But they were silent on the topic of forced arbitration.

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"No one is suggesting anyone is looking to intentionally put something dangerous on the road. But it's human nature that the less trouble we're going to get in, the less cautious we may choose to be," said Jason K. Levine, executive director of the Center for Auto Safety, a non-profit advocacy group.

"Going back 50 years, I've never seen a more brazen attempt to escape the rule of safety law, and the role of the courts to be accessible to their victims," longtime consumer advocate Ralph Nader told CNN. "With their unproven, secretive technology that's fully hackable, the autonomous vehicle industry wants to close the door on federal safety protection and close the door to the court room."

Ridesharing companies Uber and Lyft already include forced arbitration in their terms of service with passengers. Consumers will likely first experience self-driving technology in a similar format, by requesting a ride through a smartphone app.

"It's another example of large companies being able to tilt the table their way in terms of service agreements. It's a power shift created in a contract that nobody reads. Everybody clicks 'I accept,'" Walters said. "You have rights to sue unless you sign them away. And companies have gotten very good at making you sign them away."

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The largest players in the self-driving car industry, Waymo, GM's Cruise, Ford, Zoox, Toyota, Tesla, Uber and Lyft, all declined to comment for this story. The Self-Driving Coalition for Safer Streets, an industry lobbying group, also declined to comment.

"Imagine if I put my daughter in the back of a self-driving Uber to get to soccer practice, and the vehicle can't see in the fog or rain, and there's a tragedy," Levine said. "My level of ability to hold the company accountable is entirely constricted by something buried in tons and tons of pages of terms of service, for downloading the app."