Kevin Halpern filed a lawsuit in San Francisco Superior Court on Thursday claiming that Uber CEO Travis Kalanick stole the idea for a “real-time, cellular phone-based” car service from a startup, Celluride Wireless, that Halpern founded in 2003. Celluride appears to no longer be in operation, though the company is named as a plaintiff in the lawsuit, along with Halpern.

The lawsuit filed against Uber in claims that Halpern began meeting with Kalanick — whom the complaint describes as “an approachable fellow entrepreneur” — in 2006 and later shared detailed information about the ongoing development of Celluride with the future Uber co-founder. Halpern alleges that these discussions were held under the guise of confidentiality. Halpern worked until 2008 to develop the technology for Celluride, which, the lawsuit says, is similar to Uber’s business and app interface. Halpern claims Kalanick and fellow Uber co-founder Garrett Camp then stole his trade secrets and presented them as their own at a venture capital conference in the fall of 2008, which was months before the launch of Uber.

Uber said Thursday that Halpern’s lawsuit has no merit. “These claims are completely baseless. We will vigorously defend against them,” Uber spokeswoman Kristin Carvell said in a statement.

Halpern is accusing Kalanick and Camp, along with a handful of venture capital firms that back Uber, of misappropriation of trade secrets, conversion (illegally using someone else’s idea) and breach of contract. The lawsuit seeks unspecified compensatory damages. An attorney for Halpern did not immediately respond to Fortune when asked why the lawsuit was not filed until this week, more than six years after Uber’s founding. (Halpern’s attorney announced the lawsuit in a taped press conference.)

In 2009, Halpern sued Anu Shukla, the founder of tech company Offerpal Media (now called Tapjoy), for breach of contract in a similar lawsuit that alleged Halpern helped create Offerpal only to be cut out of the company shortly before it was founded. That lawsuit was later dismissed (though Halpern’s attorney told Fortune that another Offerpal co-founder, Mitch Liu, reached a settlement with Halpern), as was another one filed against two Santa Cruz police officers who arrested him for being under the influence of an illegal stimulant.

Of course, Uber is no stranger to legal action itself. The ride-sharing service has faced lawsuits from taxi companies as well as charges brought by passengers and former Uber drivers.

Successful tech companies are often the targets of lawsuits by people claiming to behind the original idea. Facebook, for example, was sued by the Winklevoss brothers, who attended Harvard with Facebook CEO Mark Zuckerberg. The brothers, who claimed Zuckerberg stole their idea for a social network, eventually won a settlement. In another lawsuit against Facebook, Paul Ceglia claimed to have a contract showing that Zuckerberg had promised him half of the company. Ceglia has since reportedly gone missing after being accused in federal court of fabricating the evidence.

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UPDATE: This story has been updated with additional information on the outcome of Halpern’s 2009 lawsuit.