Pedestrians walk past an AT&T store in the Times Square area of New York in 2016. (Michael Nagle/Bloomberg)

Wrapping up its six-week antitrust trial against AT&T, the Justice Department made a final pitch to a federal judge on Monday in calling for the telecom giant's $85 billion merger with Time Warner to be blocked — or that AT&T be permitted to buy only a portion of the media and entertainment giant.

Addressing a packed courtroom that included the chief executives of both companies, Justice Department attorney Craig Conrath cited economic analyses, industry witnesses and AT&T's own statements to support the government’s case opposing the tie-up.

The deal would add hundreds of millions of dollars a year to consumers’ TV bills, Conrath said, while restricting competition in the television industry. Addressing one of AT&T’s key justifications for the deal — the desire to compete with Facebook and Google for ad dollars — Conrath said that the benefits do not outweigh the costs to society.

“The fact that AT&T may want to compete in some other market, that doesn't give them a free pass to reduce competition in the pay-TV market,” said Conrath.

Monday’s closing arguments represent the last opportunity in the trial for both sides to make their case personally before Judge Richard Leon. Leon showed little emotion Monday morning as he occasionally scribbled notes with one hand on his chin. At times, Leon sat back in his chair, folded his arms and furrowed his brow as he listened to the government's argument.

For both sides, the trial carries high risks — and high rewards. The case is the first of its kind since President Richard Nixon’s administration, when the government successfully sued to block a merger involving Ford Motor Co. and a manufacturer of automotive spark plugs. Analysts say the outcome of the AT&T trial is likely to influence the Justice Department’s ability to bring antitrust cases in the near future  and its chances of doing so. On Sunday, T-Mobile and Sprint announced a $26 billion merger that could make the combined company the nation’s second-biggest wireless carrier.

The Justice Department has alleged that the merger would give AT&T the “incentive and ability” to use Time Warner’s content as both carrot and stick with other cable companies and TV distributors that need that programming. AT&T could use its “gatekeeper” position in the industry, said Conrath, to raise the price it charges other firms for the rights to show Time Warner’s channels, such as CNN, TBS and TNT. In price negotiations, he said, AT&T could threaten to cut off access and siphon consumers away to its own TV service, DirecTV.

AT&T has argued that it has no incentive to wield Time Warner's content anticompetitively, because Time Warner benefits the most when its content is widely distributed. It also says that the new company would be structured in ways that would limit the ability of Time Warner to coordinate with DirecTV.

AT&T and Time Warner’s lead attorney, Daniel Petrocelli, told the court Monday that the economic theory underpinning the government's case “makes no sense.” AT&T’s plan is to use its new data-driven advertising business — made possible by selling ads against Time Warner content — not only to compete against the tech industry, said Petrocelli, but to use those gains to relieve the upward pressure on consumers’ TV prices.

By making just a few adjustments to the Justice Department's economic modeling, he said, the merger could result in annual savings to consumers of $500 million.

“There are so many things wrong with that model, I could go on for hours,” Petrocelli said. He later added: “It's like ‘garbage in, garbage out … the numbers are all over the place.’ ”

As the judge nodded along to parts of his argument and asked several questions that appeared to underscore AT&T’s points, Petrocelli argued that the government presented a slipshod case, ignoring data and arguments favorable to AT&T when it was convenient and cherry-picking other numbers to undercut the merger.

When Petrocelli said DirecTV could lower its prices as a result of the merger, Leon interrupted.

“Doesn’t that create more competition in the marketplace?” he asked.

Yes, Petrocelli said, because other TV providers would have to respond to those price cuts with benefits of their own.

But Conrath said internal documents created by AT&T chief executive Randall Stephenson and others show that the company has contemplated how it could use Time Warner to give an advantage to its distribution business, such as DirecTV. As AT&T was thinking about buying Time Warner, Stephenson prepared a presentation to AT&T board members in which he jotted down a note asking precisely that question. In his witness testimony, Stephenson said that note was simply a rhetorical tool, not an actual plan to behave anticompetitively.

Reflecting on that anecdote Monday, Conrath said it seemed odd that Stephenson would think to raise that issue with the board despite later telling the court that the idea was “absurd.” Conrath also said that AT&T's own pre-merger communications with Time Warner show how “maybe that concern isn’t so absurd after all.”

Earlier in 2016, when Time Warner announced it was buying a 10 percent stake in Hulu as Hulu was preparing to launch a live, streaming video service, Stephenson had a phone call with Time Warner chief executive Jeffrey Bewkes. In Stephenson’s notes regarding the call, said Conrath, it became clear that the Hulu investment “made Mr. Stephenson worried that AT&T might not get the same Time Warner content at the same terms for [DirecTV].”

That dynamic, said Conrath, is similar to the one underlying the government’s concerns about the AT&T-Time Warner deal.

Leon said that he expects to render a decision on June 12.

Read more:

What the T-Mobile and Sprint merger means for you

What Comcast's $31 billion offer for a U.K. TV company tells us about the cable giant's ambitions

5 things AT&T revealed in the Time Warner trial that could directly affect you