• by Wendy Davis  @wendyndavis, October 26, 2021

Mozilla's Firefox browser quietly began testing the “Global Privacy Control” opt-out tool several weeks ago, and expects to roll out the feature more broadly in coming months, a spokesperson confirmed Tuesday.

The privacy tool aims to enable users to opt out of the sale or their data on a universal basis, as opposed to opting out site-by-site.

The control, which was developed by privacy advocates, was released one year ago as a downloadable extension and a setting in some browsers. When activated, the Global Privacy Control transmits a “do-not-sell” request to all websites.

California's privacy law requires companies to honor consumers' requests to refrain from selling their data, and the state's top law enforcement official says companies that collect residents' personal data must comply with opt-out requests sent through the Global Privacy Control.

Colorado also recently passed a privacy law that requires companies to honor people's requests to opt out of targeted advertising -- including requests that consumers make through browser settings or other global mechanisms.

Most provisions of the Colorado law will take effect in July 2023, but the requirement to honor global privacy controls won't take effect until the following year.

Mozilla was among the original supporters of the Global Privacy Control initiative, but didn't take steps to incorporate the feature into Firefox until recently.

A spokesperson says the company is “excited to see [Global Privacy Control] getting traction both in California and Colorado,” and is testing it now in order to “start getting experience with it in the field.”

Mozilla's Firefox browser currently blocks some tracking cookies by default but that feature doesn't universally prevent tracking, given that some ad-tech companies rely on non-cookie tracking technologies. 

The ad industry has opposed requirements that companies honor universal opt-out signals, arguing in California that the state privacy law doesn't include that mandate. The ad industry has also argued that a requirement to honor universal opt-outs violates advertisers' First Amendment rights by unreasonably burdening “commercial speech.”