A California federal judge on Monday freed Meta from an antitrust lawsuit that accused it of monopolizing an asserted market for personal social networking, saying Facebook users failed to prove the existence of an antitrust injury, with or without help from an expert witness.

U.S. District Judge James Donato of the Northern District of California ruled that the opinions of economist Nicholas Economides had to be excluded since opinions he proposed to present at trial were essentially the same ones the court already found inadmissible when it denied class certification in the case.

"They fare no better a second time around, and so are excluded from the case," Judge Donato wrote in an order on Monday.

He said the exclusion of Economides' antitrust injury opinions also "guts plaintiffs' case," thus warranting a grant of summary judgment in Meta's favor.

Judge Donato said any "lay evidence" that individual users argued would prove antitrust injury, irrespective of expert opinion, also couldn't save their case since the evidence was the same raw material Economides had reviewed for his reports.

"The problem for plaintiffs is that this evidence would not allow a jury to make a nonspeculative finding of antitrust injury any more than it allowed Dr. Economides to so opine," Judge Donato wrote. "In the hands of either a jury or an economist, documents indicating that Meta occasionally thought about paying certain users in certain situations is insufficient to provide antitrust injury, to take one example of the lay evidence."

Meta moved for summary judgment in late April, after Judge Donato denied certification for a proposed class of Facebook users who had claimed that in a "but-for" world — where Meta did not deceive users regarding how much of their data it was collecting and offering up to advertisers — other platforms would have eaten into Facebook's user base by presenting an alternative with better privacy protections.

Three remaining consumer plaintiffs sought an interlocutory appeal of the certification order, but the Ninth Circuit denied the appeal in May.

In excluding Economides' expert opinions, Judge Donato said Monday that Economides had again proposed that Meta would have paid users $5 a month but for its anticompetitive conduct.

But that assertion "is not well taken," Judge Donato said, noting that the evidence Economides presented was "essentially the same in all of his reports" and that Economides arrived at the "same inadmissible conclusion that antitrust injury occurred in the form of not paying people to use Facebook."

He said the users also didn't suggest when seeking class certification that they were presenting anything less than the best version of Economides' work.

"They were the parties seeking certification, and nothing in the record indicates that they hobbled themselves by proffering a half-baked theory of antitrust injury," Judge Donato wrote.

In granting summary judgment to Meta, Judge Donato said the users had also offered the same documents Economides had previously mentioned concerning internal discussion at Meta about paying users for data, for instance.

He said the court had already examined the offered evidence in detail and had concluded that there was an "unbridgeable gap" between the evidence and proof of antitrust injury.

"Tapping in a jury in lieu of Dr. Economides will not solve this shortcoming," Judge Donato wrote.

Judge Donato further noted on Monday that while juries can bring "profound intelligence and comprehension to even the most complicated trials," jurors still must be "properly equipped to decide highly technical issues" like antitrust injury.

"The question of antitrust injury here is exactly the type of issue that demands expert testimony to resolve, which plaintiffs cannot supply," Judge Donato said. "Consequently, Meta has demonstrated that plaintiffs cannot prove the essential element of antitrust injury at trial."

Counsel for the parties did not immediately respond to requests for comment on Monday evening.

The consumers are represented by Kevin Y. Teruya, Adam B. Wolfson, Scott L. Watson, Claire D. Hausman, Brantley I. Pepperman, Michelle Schmit and Manisha M. Sheth of Quinn Emanuel Urquhart & Sullivan LLP, by Shana E. Scarlett and Steve W. Berman of Hagens Berman Sobol Shapiro LLP, and by W. Joseph Bruckner,  Brian D. Clark, Kyle Pozan and Laura M. Matson of Lockridge Grindal Nauen PLLP.

Meta is represented by Sonal N. Mehta, David Z. Gringer, Ross E. Firsenbaum, Ryan Chabot, Paul Vanderslice, Ari Holtzblatt, Molly M. Jennings and Michaela P. Sewall of WilmerHale.

The case is Maximilian Klein et al. v. Meta Platforms Inc., case number 3:20-cv-08570, in the U.S. District Court for the Northern District of California.