• by Wendy Davis  @wendyndavis, May 14, 2015

A group of pay-per-click marketers have dropped a long-running lawsuit accusing Facebook of charging them for invalid clicks, court records reveal.

The marketers -- RootZoo, Fox Test Prep, and Steven Price (who operates the car site DriveDownPrices.com) -- didn't receive any money or other benefit in exchange for dropping the case, they say in papers filed on Tuesday with the U.S. District Court in Oakland, Calif.

The move comes five months after the 9th Circuit Court of Appeals ruled that the marketers couldn't proceed with their claims in a class-action, but could still bring suit as individuals. That decision was a significant loss for the three marketers, because their alleged losses were so small that it likely didn't make economic sense to pursue the lawsuits as individuals.

The legal battle began in 2009, when Price, Fox Test and other pay-per-click marketers sued the social networking service for allegedly charging them for invalid clicks. The marketers sued shortly after tech news site TechCrunch reported on marketers' complaints about perceived click fraud on Facebook.

When Price first filed a complaint, he alleged that Facebook billed him $500 for ads that appeared May 26 and June 21, 2009, but that analytics programs from Google and Statcounter.com showed that two-thirds of the clicks he was charged for didn't take place.

He said that Facebook acknowledged that it had charged him for invalid clicks and gave him $105.01 in credits, but argued that he was entitled to a refund.

The sports site RootZoo also originally alleged that it found discrepancies between data provided by its own analytics programs and Facebook's numbers. For instance, the company said that on one day in June of 2009, its software programs showed that 300 clicks had been generated by Facebook, but the company was charged for 804 clicks.

U.S. District Court Judge Jeremy Fogel in San Jose, Calif. ruled several years ago that Facebook's contract with marketers disclaimed liability for clicks that were "fraudulent," in the sense that the clicker had dubious intentions. But Fogel ruled that the disclaimer didn't apply to clicks that were "invalid" -- such as when technical problems kept users from reaching a landing page.

A different judge, Phyllis Hamilton, ruled in 2012 that RootZoo and the other marketers couldn't bring the lawsuit as a class-action, because the marketers hadn't shown a “uniform method” for determining which clicks were invalid. Hamilton also said that damages were likely to be different in every case.

The 9th Circuit upheld the decision last December, ruling that the marketers hadn't shown a “workable class-wide methodology” for determining whether clicks were valid.