Google on Monday began confronting an existential threat as the U.S. government tries to break up the company as punishment for turning its revolutionary search engine into a ruthless monopoly. The drama began to unfold Monday in a Washington courtroom as three weeks of hearings kicked off to determine how the company should be penalized for operating an illegal monopoly in search. The proceedings, known in legal parlance as a "remedy hearing," feature a parade of witnesses that includes Google CEO Sundar Pichai. The moment of reckoning comes four-and-a-half-years after the U.S. Justice Department filed a landmark lawsuit alleging Google's search engine had been abusing its power as the internet's main gateway.

A judge on Monday ruled that Google's ubiquitous search engine has been illegally exploiting its dominance to squash competition and stifle innovation in a seismic decision that could shake up the internet and hobble one of the world's best-known companies. The highly anticipated decision issued by U.S. District Judge Amit Mehta comes nearly a year after the start of a trial pitting the U.S. Justice Department against Google in the country's biggest antitrust showdown in a quarter century. After reviewing reams of evidence that included testimony from top executives at Google, Microsoft and Apple during last year's 10-week trial, Mehta issued his potentially market-shifting decision three months after the two sides presented their closing arguments in early May.