Uber is once again facing tough questions about safety after one of its drivers was charged with murder.
The fast-growing, San Francisco-based ride-hailing company defended its screening of drivers on Monday, saying it couldn't have predicted that driver Jason Dalton would engage in the random shootings that left a half-dozen people dead in Kalamazoo, Michigan, on Saturday night.
Uber said its safety procedures are robust and don't need to change.
But some experts say the company needs to take a harder look at potential drivers if it wants to convince riders the service is safe, even as they agreed that Dalton wouldn't have raised red flags because he didn't have a criminal record.
The shootings began on Saturday evening and took place over nearly five hours.
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The Kalamazoo County prosecutor says Dalton picked up Uber passengers after the first shootings and probably after subsequent shootings.
Uber security chief Joe Sullivan said Dalton cleared a background check and was approved to be a driver on January 25.
He had given slightly more than 100 rides and had a rating of 4.73 stars out of a possible five.
Until Saturday, Sullivan said, Uber had no reason to believe anything was amiss.
Still, the incident raised more questions about Uber's security.
The company earlier this month agreed to pay $US28.5 million ($A39.39 million) to settle two lawsuits that alleged it misled customers about safety procedures and fees.
It's also facing a separate a lawsuit by district attorneys in San Francisco and Los Angeles, who alleged that Uber's checks failed to prevent the company from hiring several felons.
In response to the lawsuits, Uber has stopped using terms like "safer than a taxi" and "industry-leading background checks."
But it insists riders are protected, and points out that, unlike taxis, riders can rate drivers.
Uber's driver background checks compare names to public court records and are far less effective than fingerprint checks that access the FBI criminal history database, says Matthew Daus, a former New York City Taxi Commissioner and a transportation lawyer who has studied the issue.
Name checks can miss court records if a person uses an alias or their name is even slightly different from the records, Daus said.
Uber disputes that, and says the FBI records can be flawed because they don't always make clear cases in which charges were dropped.
