On Saturday, The Wall Street Journal reported that investigators from the Department of Justice will examine “Google’s business practices related to its search and other businesses.” It’s one of the biggest threats Google has ever faced from US regulators, but so far, we don’t know much about the case itself. The Journal’s description was open-ended, and the nature of Google’s business makes it vulnerable to antitrust challenges from a number of different directions. Google dominates the search market, but it also holds nearly 40 percent of the digital advertising market, and Android is the world’s most popularoperating system. In all of these markets, critics have claimed that Google is simply too big, and it’s faced billion-dollar fines over each of them in Europe.
The probe is supposedly in its early stages, and it’s not clear what the Justice Department might consider worth investigating. But the earlier EU fines, along with a 2013 Federal Trade Commission investigation, offer some guidance. We’ve broken down some of the major monopoly allegations against Google as well as how courts and regulators have treated them so far — from search engine rankings to Android app bundling. (Google, perhaps understandably, did not respond to a request for comment.)