You may have heard the phrase “dark patterns” as shorthand for various user interfaces designed to influence users’ decisions. They can range from the perfectly innocent to the unethical, and even illegal. Whatever the form, dark patterns have recently drawn attention from the mainstream press.

Dark patterns are coming out from the shadows. And when that happens, class action lawyers can’t be far behind.

What are they?

“Dark patterns” has been used to describe, for example, hidden costs revealed just before clicking “Purchase,” or buying one installment and getting secretly auto-enrolled on a subscription. These things already violate Section 5 of the FTC Act and most state consumer protection laws. But what about a hotel that falsely suggests rooms are getting booked, prompts like “Suzie from Altoona just saved $58 on her order” where someone may have made that purchase but it was not a “Suzie from Altoona,” websites or apps that bury important instructions (e.g., how to quit) under layers of sub-clicks, or suggesting a product is on sale or in limited supply when the pop-up refreshes every time the user revisits? It’s less clear whether these practices violate existing law.

It’s not only sales, either. For example, the GDPR defines “consent” as “any freely given, specific, informed and unambiguous indication of the data subject’s wishes by which he or she, by a statement or by a clear affirmative action, signifies agreement to the processing of personal data relating to him or her.” Consequently, companies relying on consent as their legal basis for processing personal data in the EU should consider how dark patterns may impact their consents.

The term “dark patterns” lends a bad name to a wide variety of business practices, but, as noted, not all of these things violate the law. Most don’t, although the EU’s Consumer Rights Directive goes farther than most U.S. laws in banning some dark pattern practices.

How big is the problem?

A Princeton research group recently issued a report on 11,000 of the most popular shopping websites. It claims to have found instances of dark patterns in 11.2% of them. Moreover, it found dozens of third-party entities that offer turnkey solutions enabling sellers to build dark patterns into their websites.

As with dark patterns generally, the report indicates that more than a thousand shopping websites used methods ranging from the annoying-but-innocent to the downright unlawful. The report doesn’t name names.


In April, Senators Mark Warner (D. Va.) and Deb Fischer (R. Neb.) introduced bipartisan legislation called the Deceptive Experiences to Online Users Reduction Act (DETOUR Act), which would bar internet firms with over 100 million monthly active users from engaging in certain dark patterns. Specifically, companies wouldn’t be allowed to develop interfaces with the “substantial effect” of preventing users from making an informed decision before handing over personal data. The DETOUR Act would also require disclosure of experiments to users and the public at least once every 90 days, and would mandate independent review boards for any behavioral or psychological research. And it would prohibit user designs intended to create compulsive usage among children under the 13 years of age. There are some obvious problems with defining the conduct that would be unlawful under this bill, and implementation of any such prohibitions would be very controversial. But this is unlikely to be the last time Congress or state legislatures take an interest in this area.