Liss-Riordan has focused on Uber's tipping practices before, first in a 2012 case she filed on behalf of Boston drivers alleging skimmed tips, and later in a class-action lawsuit filed in 2013 accusing Uber of manipulating fares by telling customers that tips are included, but then keeping part or all of them. Following these suits, Uber has backed away from explicit claims that tips are included but has continued to discourage tipping, says Liss-Riordan. She calls their racial bias argument against tipping "ridiculous," because "workers in the service industry rely on tips. It's an important part of their income. Customers should be encouraged to supplement the meager pay of Uber drivers."