This article provides an overview of economic analysis in three prominent merger investigations and litigations: Electrolux's proposed acquisition of General Electric's appliance division, Halliburton's bid for Baker Hughes, and United Airline's attempt to acquire additional airport slots at Newark Liberty International Airport. In each, the parties abandoned their proposed transaction after the Division had filed suit to block the acquisition. While we cannot recount all the analyses underpinning these outcomes, we hope to provide some insights into the challenges of enforcing antitrust law and the way in which economic analysis in particular is used to address those challenges.