Peter Dinklage and Conleth Hill in a scene from Game of Thrones.
Judge Leon reportedly put no conditions on the deal and the result of this case stands to have far-reaching effects on the media landscape and other groups considering or seeking vertical mergers.
To see how this could happen, consider that, after the merger, AT&T would have the rights to all of HBO's output, CNN, live National Basketball Association and NCAA broadcasts, and many more desirable Time Warner properties.
Analysts say the decision will bolster firms such as Comcast - which is considering bidding for 21st Century Fox assets, including its stake in Sky, in a challenge to a deal announced between Fox and Disney a year ago.
It is worth remembering that the Justice Department is reviewing the T-Mobile/Sprint combination, and the Justice Department did not approve AT&T's purchase of Time Warner.
Market players say they're expecting AT&T's go-ahead to unleash further M&A activity down the road - much of which will be funded in the credit markets. Delrahim, Trump's appointment as the antitrust chief at the Justice Department, is widely well-regarded. AT&T said just the opposite-it was buying all that content to lower its costs and to create more futuristic services, like a mobile app that mashes up news clips from CNN into a personalized video news feed for every viewer or a mini-package of cable channels watchable on a mobile phone for $15 a month.
The merger, if permitted by Judge Richard Leon, is widely considered to be a harbinger of future media mergers that could radically shift how Americans consume television and movies going forward.
A high-stakes decision in a U.S. court Tuesday will be significant for the future of Big Media, Big Tech and big business in general.
And the AT&T-Time Warner deal is not necessarily yet in the clear.
"The government's evidence is too thin a reed for this court to find that AT&T has, in that well worn turn of phrase, either the "incentive" or the "ability" to withhold HBO promotional rights in order to 'lessen competition substantially'".
A US court ruled that AT&T's deal for media giant Time Warner could go ahead over the objections of the US Department of Justice, which anxious that the combination would raise prices for consumers. "Small wonder it had to go to trial!"
AT&T refused to divest assets and the Justice Department sued to block the deal in November. Deals such as this one, in which the two companies are in related industries but do not produce competing products, are usually approved by federal regulators.
David McAtee, AT&T general counsel, said: "We are pleased that, after conducting a full and fair trial on the merits, the court has categorically rejected the government's lawsuit to block our merger with Time Warner".