• by Wendy Davis  @wendyndavis, February 10, 2015

Verizon and ad company Turn have been hit with a potential class-action lawsuit centering on their use of a controversial technology that subjects consumers to tracking for online ad purposes, even when they delete their cookies.

The lawsuit, quietly filed last week by Jackson, Miss., resident Emma Michael, stems from a report last month that outlined how Turn tracked Verizon users' Web activity by drawing on headers that Verizon injects into mobile traffic. The headers, called UIDHs, enable ad companies to compile profiles of users and serve them targeted ads.

The UIDHs also are known as “zombie” cookies because they allow ad companies to recreate cookies that users delete.

Michael argues in her complaint, brought in U.S. District Court in Jackson, that Verizon and Turn are violating several laws, including a computer fraud law and a video-privacy law.

She says that Verizon users “consider information about their online activities to be confidential.”

“To avoid being tracked online, plaintiff and class members have used and relied on their browser controls to block and/or delete browser cookies,” she alleges. Michael adds that she “reasonably believed” that she could rely on her browser settings to control cookies.

Verizon uses the UIDHs to track people's activity online and send them targeted ads. The company has always allowed people to opt out of receiving targeted ads powered by its own ad programs, but didn't previously allow users to avoid header injections. The telecom now says it intends to let customers opt out of the headers.

Last year, privacy advocates raised concerns that outside ad companies could draw on the UIDHs to target Verizon users. At the time, Verizon dismissed that scenario as unlikely.

But last month, Stanford's Jonathan Mayer published research showing how Turn leveraged the headers for its behavioral advertising program. Several days later, Turn said it would stop doing so.

Privacy advocates are urging Verizon to abandon the UIDHs completely, or else make the program opt-in.

A group of lawmakers recently asked the Federal Trade Commission and Federal Communications Commission to investigate Verizon's use of the headers.

Verizon and Turn declined to comment on Michael's lawsuit.