The questions being raised about the handling of customer data by Uber and Lyft are the latest in a string of problems smartphone apps based ride-hailing companies face as their business model comes under criticism from traditional taxi companies and regulators.
The Minnesota senator, who is also chairman of the Senate Subcommittee on Privacy, Technology, and the Law, wrote in a letter Tuesday to Lyft CEO Logan Green that consumers should be able to decide whether and with whom they share their personal data, and must be assured that when data is shared it will be well protected.
"In few places is the importance of this as apparent as with companies, such as Lyft, that employ new technologies and rely on the transmission of sensitive data," he added.
A report last month in The Wall Street Journal quoted a Lyft spokeswoman as claiming that the company's longstanding internal policy bans employees or contractors from accessing user data unless it is necessary to do their job.
In the letter to Green, Franken wants to know which categories of employees continue to have access to customer data, including location data, and under which conditions their use of the data is considered proper. The Senator also wants to know what mechanisms the company has in place to monitor for the improper use of the data and to penalize such use, and whether customers would be informed of breaches.
"At least one journalist has reported that her trip log was accessed on multiple occasions by Lyft executives without requesting her permission and without any apparent legitimate business purpose," Franken wrote, referring to a news report in Re/code.
The Democrat Senator has also asked Green for information on why customers are not asked for their consent before data is shared with advertisers, and whether customers can opt out from this data sharing. Franken also asked Green why trip information was stored indefinitely, rather than maintained until pending charges or transaction disputes are settled.
"We share Senator Franken's dedication to keeping consumers and their information safe. People nationwide have embraced Lyft because of the improved accountability and transparency built into the platform, and we have continued to upgrade our existing privacy safeguards.," Lyft said in an emailed statement.
"The respect and rights of our users are at our core as a company, and we look forward to discussing this important issue and Lyft's commitment to consumer privacy in depth," it added.
In his letter to Uber last month, Franken asked, also in ten questions, for information on the company's privacy policies, including who in the company and for what reason had access to a so-called "God view" tool that, according to a report, lets employees track the location of customers who have requested the car service.
Franken has asked Lyft for a reply by Dec. 31.
John Ribeiro covers outsourcing and general technology breaking news from India for The IDG News Service. Follow John on Twitter at @Johnribeiro. John's e-mail address is john_ribeiro@idg.com