The Justice Department has filed a massive antitrust lawsuit against Google, accusing the internet behemoth of using its market power to hamper rivals. The suit signals the formal start of a lengthy legal war between Washington and Silicon Valley, with vast implications for the wider tech sector. The lawsuit alleges that Google broke the law in how it treated rivals in its search and advertising businesses, seeking to disadvantage them to keep its own search engine dominant and use that market power to sell more ads. The timing could be seen as fulfilling Donald Trump’s pledge to hold certain companies to account for allegedly stifling conservative voices. The Justice Department and Federal Trade Commission also have antitrust investigations into Amazon, Apple, and Facebook. In Europe, competition regulators have slapped Google with $9 billion in fines and forced major operational changes on the business.