ALEXANDRIA, Virginia (Reuters) -The U.S. judge considering whether to order a breakup of Google's advertising technology business asked the Department of Justice on Friday how quickly such a remedy would take effect, saying, "time is of the essence."

Google has so far come away largely unscathed from a bipartisan government legal crackdown on the dominance of Big Tech - a push that began during the first term of President Donald Trump.

But that could change, depending on what U.S. District Court Judge Leonie Brinkema in Alexandria, Virginia, decides in the DOJ's case over Google's ad tech.

At closing arguments in the case on Friday, the judge brought up the fact that Google will seek to appeal the case, a move that would likely push any forced sale years down the road.

"The kind of request you are making most likely would not be as easily enforceable while an appeal is pending," the judge said.

Brinkema ruled in April that Google holds two illegal ad tech monopolies, and is now considering what the company must do to restore competition.

Google is "in an impossible situation" and very likely to appeal that ruling, Brinkema said, given the fact that publishers and rival ad tech companies are relying on the ruling to seek damages in several new lawsuits.

The DOJ and a coalition of states have asked the judge to make Google sell its ad exchange, AdX, where online publishers pay Google a 20% fee to sell ads in auctions that happen instantly when users load websites.

DOJ attorney Matthew Huppert argued on Friday that nothing short of a forced sale would bring a "brighter, more competitive future for the open web."

The court's remedy "needs to eradicate Google's illegally acquired monopolies root and branch," he said.

Google's attorney, Karen Dunn, argued a forced sale would be too extreme a measure.

"Lawfully acquired monopoly power is the foundation of the American economy," she said, citing a 2004 Supreme Court ruling.

A breakup would be technically difficult, resulting in a long and painful transition that would hurt customers, Dunn argued.

The closing arguments on Friday mark the end of evidentiary hearings in Google's years-long battle with the DOJ over its dominance in online advertising and search. Next, Google has said it will file appeals.

The U.S. still has antitrust cases pending against Amazon and Apple.

A judge recently rejected the Federal Trade Commission's bid to make Meta Platforms sell off Instagram and WhatsApp. The agency has not said whether it will appeal.