Already one deal depends on the ruling: Comcast Corp said in May that it was preparing a higher, all-cash offer for most of the media assets of Twenty-First Century Fox, but sources say it will only proceed if AT&T wins its case.
The Justice Department, mostly under President Obama, has won nine of the last 10 lawsuits it has filed to stop mergers, records show.
U.S. District Judge Richard Leon said the government failed to meet its burden of proof in its antitrust suit against the AT&T-Time Warner merger.
The case has drawn attention from all sides including Sling TV's President Warren Schlichting, who testified against the merger.
"We would lose a lot of subs", Schlichting said, during an hour and a half of testimonies at the U.S. District Court in Washington, D.C.
"AT&T is buying Time Warner, and thus CNN", Trump said at a campaign rally in 2016. However, now that the AT&T deal has been approved by a federal judge, there is precedent for such a deal and Comcast believes it won't be blocked.
"The government here has taken its best shot to oppose this merger", Leon said, speaking to a packed courtroom in an unusual session weeks after the trial ended. The ruling could open the floodgates to deal making in the fast-changing entertainment and video-content worlds.
Judge Richard Leon said the USA government failed to meet the burden of proof that the tie up between the largest United States pay TV operator and media entertainment giant Time Warner would harm competition.
Even so, the case brought previous year by the antitrust lawyers at Trump's Justice Department to block the AT&T and Time Warner marriage is an outlier.
Rival cable company Comcast is now likely to go ahead with its planned attempt to woo Twenty-First Century Fox Inc away from Walt Disney Co, which said it would acquire most assets of the media company for around $50 billion past year.
The DOJ argued that buying Time Warner and its stable of popular TV programming would give AT&T too much control over programming and distribution. Looming in the background of the deal has been Trump's long-running feud with Time Warner's CNN, which he has often derided as "failing" and a purveyor of "fake news". The "drop dead" deadline for the merger to be completed is June 21. The companies' CEOs, AT&T's Randall Stephenson and Jeffrey Bewkes of Time Warner Inc., testified in support of the deal.
"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", said David McAtee, AT&T General Counsel.
AT&T and Time Warner said they need to combine in order to better compete with Facebook (FB), Amazon (AMZN), Apple (AAPL), Netflix (NFLX) and Google (GOOG), companies that are already powerhouses in the content game. AT&T wasn't on board, saying, "Divestitures here would destroy the very consumer value this merger is created to unlock".
"We are disappointed that the court missed an opportunity to rein in the First Amendment-crushing mass media consolidation trend, which puts too much media power in the hands of too few", Manning said in a statement.