NEW YORK - US search engine giant Google took 15 years to make deletion the default in its internal communications, creating an office culture that tried to minimize its own information, reported The New York Times on Wednesday.

"Among its tools: Using legal privilege as an all-purpose shield and imposing restraints on its own technology, all while continually warning that loose lips could sink even the most successful corporation," noted the report.

How Google developed this distrustful culture was pieced together from hundreds of documents and exhibits, as well as witness testimony, in three antitrust trials against the Silicon Valley company over the last year, according to the report.

"The exhibits and testimony showed that Google took numerous steps to keep a lid on internal communications," said the report. "It encouraged employees to put 'attorney-client privileged' on documents and to always add a Google lawyer to the list of recipients, even if no legal questions were involved and the lawyer never responded."

ALSO READ: US govt 'will push Google to sell Chrome' to break search monopoly

Companies anticipating litigation are required to preserve documents. But Google exempted instant messaging from automatic legal holds. If workers were involved in a lawsuit, it was up to them to turn their chat history on. From the evidence in the trials, few did, it added.

The report came out as US prosecutors argued to a judge on Wednesday that Google must sell its Chrome browser, share data and search results with competitors and take a range of other measures to end its monopoly on searching the internet.

Such changes would essentially result in Google being highly regulated for 10 years, subjecting it to oversight by the same Washington federal court that ruled the company maintained an illegal monopoly in online search and related advertising.

Google controls about 90 percent of the online search market.

ALSO READ: US considers breakup of Google in landmark search case

"Google's unlawful behavior has deprived rivals not only of critical distribution channels but also distribution partners who could otherwise enable entry into these markets by competitors in new and innovative ways," the US Department of Justice said in a court filing.

The court papers filed Wednesday night expand on an earlier outline on how the US wants to end Google's monopoly. Google called the proposals radical at the time, saying they would harm US consumers and businesses and shake American competitiveness in AI. The company has said it will appeal.

The DOJ demands are wide-ranging, including barring Google from re-entering the browser market for five years and insisting Google sell its Android mobile operating system if other remedies fail to restore competition. The DOJ has also requested a prohibition on Google buying or investing in any search rivals, query-based artificial intelligence products or advertising technology.

The DOJ and a coalition of states want US District Judge Amit Mehta to end exclusive agreements in which Google pays billions of dollars annually to Apple and other device vendors to make its search engine the default on their tablets and smartphones.

READ MORE: US judge orders Google to open up app store to competition

Google will have a chance to present its own proposals in December.

Mehta has scheduled a trial on the proposals for April, though President-elect Donald Trump and the DOJ's next antitrust head could step in and change course in the case.