When Google advertisers sign up for AdWords they encounter two adjacent boxes. The first asks how much the advertiser is willing to pay per click for ads in Google search results. The second, labeled optional, asks how much the advertiser is willing to pay per click for ads on third party networks. If you leave the second box blank, Google assumes you'd pay the same price that you entered into the first box. Lawyer Brian Kabateck calls that a false assumption and he's filed a federal class action lawsuit in San Jose seeking damages.