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.
"We are grateful to the court for seeing it the way we did", Gindseberg said. Now that yesterday's AT&T ruling will ease the approval pathway for a Comcast deal, Fox may need to take another look at any Comcast offer. A loss for AT&T and Time Warner could have signaled a new era of government scrutiny over so-called "vertical mergers" and could have halted attempts by companies like Disney, Fox and Comcast to announce their own megadeals.
Using unusually strong language, Leon said it would be "manifestly unjust" for the government to ask him to put his own ruling on hold, because if he were to do so, it could have the effect of killing the deal, which has a deadline for completion of June 21.
"Consumers may not notice the difference if this one deal goes through because they are already getting crushed in the marketplace", added Susan Crawford, a professor at Harvard Law School and author of Captive Audience on the Comcast/NBCUniversal merger.
Harry Litman is the former United States attorney for the Western District of Pennsylvania and deputy assistant attorney general in the Department of Justice.
Fox, whose biggest shareholder is media tycoon Rupert Murdoch, has a 39% stake in Sky and has been trying to buy it outright, with the intention of selling the full company to Disney as part of that deal.
Some critics of President Trump have questioned whether the case was brought as political payback against Time Warner's CNN for unfavorable coverage of President Trump, who often called the cable news channel "fake news".
FOX Business Network senior correspondent Charles Gasparino was first to report that Comcast was planning to announce its bid after market close.
Honest, direct and productive meet with North Korean leader, says US President
Ultimately, Trump has just willingly sat down with a villain and not gained much in the way of concessions in return. There was some confusion in the USA over precisely what military cooperation Mr Trump had promised to halt.
Still, the AT&T court fight gave Comcast valuable information about how to structure a Fox deal, said David Scharf, a litigation expert with Morrison Cohen.
The decision is a huge loss for the Justice Department, which broke from recent tradition by challenging the vertical merger, which involves two companies that don't compete directly with each other.
A U.S. federal judge was set to announce his verdict in the $85 billion merger of wireless and broadband giant AT&T with media-entertainment conglomerate Time Warner. The sheer scale of the deal is what led the Justice Department to file an antitrust lawsuit to try to prevent the merger.
AT&T and Time Warner's lead lawyer, Daniel Petrocelli, said outside the courthouse that the companies were gratified and relieved.
Consumer advocacy groups denounced the ruling, arguing that it could enable AT&T to thwart competition from online video distributors - especially now that the Obama-era net neutrality rules have been repealed.
The ruling comes with other big mergers awaiting review. It was, Trump said, "a deal we will not approve in my administration".
Shares of AT&T were about flat in after-hours trade following the decision, while Time Warner rose more than 5 percent.