Many websites have used tracking pixels to see what visitors look at and for how long for more than a decade, and many acknowledge that in terms of service documents. Consumer advocates have argued that using web visitor tracking technology without drawing visitors' attention to the tracking very forcefully may violate the visitors' privacy rights, and that tracking visitors without providing even more forceful warnings might violate state and federal Health Insurance Portability and Accountability Act health information privacy rules.

Hahn and Tendick "had their personally identifiable information and protected health information disclosed to Meta and Google without their express written authorization or knowledge," the plaintiffs say in their complaint.

The plaintiffs are hoping the eligible users will be those who still have the legal ability to file a suit, based on the laws governing the time limits for web visitor privacy suits, and Aug. 1, 2024.

The plaintiffs have accused VSP of violating the federal Electronic Communications Privacy Act, "which prohibits the intentional interception of the contents of any electronic communication"; violating the California Invasion of Privacy Act, for California residents; and conversion of the web visitors' internet browsing data and sensitive health information for web tracking use without the web visitors' consent.

The plaintiffs may have filed the suit in Illinois partly because the state is known for having a tough state biometric privacy law.

California is another popular location for lawyers bringing web tracking suits.

The plaintiffs in the new VSP suit want to create one class for VSP site users covered by the California Invasion of Privacy Act and a second class for other VSP site users.

The plaintiffs are asking for a jury trial.

Attorneys for VSP have not yet appeared in court and representatives for the company were not immediately available to comment on the suit.