The tech sector has been a particular challenge for antitrust enforcers and the courts because the industry evolves rapidly and many products and services are offered free to consumers, who in a sense pay with the valuable personal data companies such as Google collect.

The search company famously outmaneuvered the Federal Trade Commission nearly a decade ago.

The FTC, which shares antitrust authority with the Justice Department, spent more than a year investigating Google but decided in early 2013 not to bring a case in response to complaints that the company engaged in "search bias" by favoring its own services and demoting rivals. Competition staff at the agency deemed the matter a close call, but said a case challenging Google's search practices could be tough to win because of what they described as mixed motives within the company: a desire to both hobble rivals and advance quality products and services for consumers.

The Justice Department's case doesn't focus on a search-bias theory.

Google made a handful of voluntary commitments to address other FTC concerns, a resolution that was widely panned by advocates of stronger antitrust enforcement and continues to be cited as a top failure. Google's supporters say the FTC's light touch was appropriate and didn't burden the company as it continued to grow.

The Justice Department's current antitrust chief, Makan Delrahim, spent months negotiating with the FTC last year for jurisdiction to investigate Google this time around. He later recused himself in the case -- Google was briefly a client years before while he was in private practice -- as the department's top brass moved to take charge.

The Justice Department lawsuit comes after internal tensions, with some staffers skeptical of Attorney General William Barr's push to bring a case as quickly as possible, the Journal has reported. The reluctant staffers worried the department hadn't yet built an airtight case and feared rushing to litigation could lead to a loss in court. They also worried Mr. Barr was driven by an interest in filing a case before the election. Others were more comfortable moving ahead.

Mr. Barr has pushed the department to move forward under the belief that antitrust enforcers have been too slow and hesitant to take action, according to a person familiar with his thinking. He has taken an unusually hands-on role in several areas of the department's work and repeatedly voiced interest in investigating tech-company dominance.

If the Microsoft case from 20 years ago is any guide, Mr. Barr's concern with speed could run up against the often slow pace of litigation.

After a circuitous route through the court system, including one initial trial-court ruling that ordered a breakup, Microsoft reached a 2002 settlement with the government and changed some aspects of its commercial behavior but stayed intact. It remained under court supervision and subject to terms of its consent decree with the government until 2011.

Antitrust experts have long debated whether the settlement was tough enough on Microsoft, though most observers believe the agreement opened up space for a new generation of competitors.

--Ryan Tracy contributed to this article.

Write to Brent Kendall at brent.kendall@wsj.com and Rob Copeland at rob.copeland@wsj.com

(END) Dow Jones Newswires

10-20-20 1034ET