Ringleader describes the Media Stamp as “the mobile equivalent of an online cookie” and provides “persistent (across sessions, carriers, networks, domains, etc.) and anonymous device identification”.

According to the lawsuit, when a consumer uses his or her mobile device to access a website where Media Stamp is used, the technology collects a range of information about the device and its browser configuration in order to create a global unique ID.

The lawsuit claims that with this ID Ringleader, advertisers, ad agencies and website publishers can “track a user’s web browsing movements across the entire internet and not just one particular website”.

Plaintiffs allege that deleting cookies and browser history – commonly used means of preventing tracking – has no impact on Media Stamp as its unique ID is stored elsewhere within the browser.

On its website, Ringleader Digital states that Media Stamp has enabled “advanced privacy controls to let consumers persistently opt out of tracking for the life of their device”.

However, the lawsuit alleges that most of the privacy policies belonging to Media Stamp clients named in the complaint “inadequately inform” consumers of the extent they are being tracked “by an unidentified third party”.

According to the complaint, “most of the defendants’ sites fail to address or identify Ringleader and Media Stamp at all”. Meanwhile, plaintiffs claim Ringleader’s own privacy policies leave readers with the impression that the company’s monitoring techniques “are no different than the good old cookies people are familiar with and know how to block”.

The class action complaint names Ringleader and customers including CNN, Whitepages and mobile ad and analytics network Medialets, among others.

In a statement sent to Wired.com, Ringleader CEO Bob Walczak said: “To the extent that the plaintiffs are alleging that Ringleader violated any laws relating to consumers’ privacy, Ringleader intends to defend its practices vigorously.”

News of the lawsuit follows legal action brought by consumers against companies including Quantcast and Clearspring over their use of Flash cookies.