The U.S. government and 17 states sued Amazon on Tuesday in a landmark case that could take down the tech giant.The Federal Trade Commission and a bipartisan group of state attorneys general say that Amazon is a monopolist that chokes competitors and raises costs for both sellers and shoppers.Lina Khan, the head of the Federal Trade Commission, has spent years arguing that a few big companies have too much control over corporate America. The new lawsuit against Amazon is the biggest test of these arguments yet. NPR's Ari Shapiro talks to FTC Chair Lina Khan, the driving force behind the case.