• by Wendy Davis , Staff Writer @wendyndavis, February 1, 2017

An industry watchdog is warning ad companies that it will begin enforcing a self-regulatory privacy code for cross-device tracking.

The code, unveiled in November of 2015, requires ad networks, publishers and other companies to notify consumers if data about them is collected across more than one computer -- like a smartphone or tablet -- in order to serve ads to different devices used by the same consumers.

The code also generally requires online companies engaged in that type of "cross-device" to let users opt out of receiving behaviorally targeted ads. That restriction means that if a user opts out on a laptop, marketers can't use data collected from that laptop to serve "interest-based ads" on any device linked to the person -- including smartphones and tablets associated with that user.

"We think of the opted-out device as a 'black hole' from which no data for IBA [interest-based advertising] can escape and into which no IBA ads can go," the Better Business Bureau's Online Accountability Unit says in a compliance warning issued today.

The code has come in for criticism because it doesn't require companies to let consumers opt out across all devices with a single mechanism.

The watchdog addresses that concern in its compliance warning by stating that not all companies are able to offer that kind of opt out for technological reasons. The enforcement unit also posits that "there may be reasons that a particular consumer does not want an opt out to apply to all of her devices." The group doesn't speculate about what those reasons might be.

The new enforcement initiative comes several weeks after the Federal Trade Commission issued a report raising questions about whether Web publishers disclose policies regarding cross-device tracking. The report said that many Web sites share the kind of information about consumers that could allow them to be tracked across more than one device, but that few sites clearly spelled out their policies regarding that kind of tracking.