Over the past two and a half weeks, Google has called a dozen witnesses to defend itself against claims by the Justice Department and a group of state attorneys general that it illegally maintained a search and advertising monopoly, in a landmark antitrust case that could reshape tech power.

Google’s lawyers are set to wrap up their arguments in the case — U.S. et al. v. Google — on Tuesday, which will be followed by a government rebuttal. Judge Amit P. Mehta of U.S. District Court for the District of Columbia, who is presiding over the nonjury trial, is expected to deliver a verdict next year after both sides summarize their cases in writing and deliver closing arguments.

The company’s main defense has centered on how its actions were justified and how it helped consumers and competition. Here are Google’s main arguments.

How Google’s actions were justified

• It paid Apple an appropriate (and undisclosed) amount of money

It has invested more than search rivals in making its product great

One thrust of Google’s defense was that its focus and investments in search did not harm consumers and others, as the government has tried to argue, but instead brought benefits.

• Its innovations have helped consumers around the world

• Its actions have been competitive on balance, not anticompetitive

Amazon, where consumers look for information online.

Google’s lawyers argued at the trial that rivals had been able to win contracts but could not hold on to them because of the poor quality of their products.

Additionally, the company’s employees testified that it balanced its pursuit of revenue from each ad with ensuring that users generally saw high-quality ads in its search results.