Last October I sat through a speech by Wired UK editor David Rowan in which he argued that consumers increasingly view their personal data and their social media footprint as valuable. “They know they can gain by trading their private information [with companies],” he said.

This prompted me to consider what research companies might have to offer by way of trade, to ‘buy’ access to information such as people’s opinions, shopping habits, web browsing behaviours and media usage. You can read my thoughts on that here.

My reason for returning to this topic now is that the concept of personal information as trading currency is about to be tested in court in a case brought by Facebook users angry at an alleged leak of their names via referrer headers sent by the social network to their advertisers.

Earlier this year Facebook sought to have the lawsuit dismissed, arguing that users weren’t harmed by the alleged leak. But plaintiffs in the case recently hit back.

“Facebook revealed specific information about specific Facebook users to advertisers in violation of Facebook’s contracts with the affected users and in violation of state and federal laws,” plaintiffs’ court filings claim. “What makes this wrong legally redressable is that the information revealed was specifically bargained for: Facebook promised to safeguard this information and provide access to Facebook in exchange for the information itself. In other words, plaintiffs used this information as currency to obtain access to Facebook.”

The site itself makes money from users’ personal information, by targeting ads at relevant consumer groups, but it promises to keep user data private. By failing to do so, the plaintiffs allege, they have “lost the right to provide that data to entities in exchange for goods and services, because these entities have received the information from Facebook”.

If this argument succeeds it will be interesting to see how much value is assigned to these “lost” trading rights. And once we know how much personal information is worth, might it make survey respondents a lot more demanding about the incentive they get for taking part in research? Time, again, to start considering the question “What’s in it for them?”