On Tuesday, the Department of Justice filed an antitrust case against Google. This is the most significant antitrust case filed since the government suit against Microsoft in 1998, and it also ranks with the most important antitrust suits of all time, including Standard Oil and AT&T. The move by a conservative Republican administration to take on one of the largest companies in the world is a repudiation of the libertarian ideology that has dominated American politics since the 1980s.

Why is this case such a big deal? Let’s start with Google itself. Google is a monster in both size and behavior. It is worth over $1tn and has $160bn of revenue. It has nine products with more than a billion users each, and it dominates search, maps, online video, email, browsers and mobile phone operating systems. But just as there’s no Standard Oil without oil, there’s no Google without search. Google has roughly 90% of the mobile search market and has had a dominant share of search since the early 2000s.

Search and advertising are not mere products like cars or refrigerators; search and advertising represent the flow of information in a free society. America, and the world, has never seen this kind of radical centralization of information flow and ad financing. As Senator Ted Cruz has put it, Google is “larger and more powerful than Standard Oil was when it was broken up by the antitrust laws”.