A federal judge issued an injunction against the Federal Trade Commission ordering it to stop an investigation into left-wing group Media Matters, saying the Trump administration illegally retaliated against the group for its liberal activism.

Judge Sparkle Sooknanan, a Biden appointee to the bench in Washington, said a who’s who of major Trump figures had vowed to go after Media Matters and so when the FTC did so, it was tainted from the start.

“This case presents a straightforward First Amendment violation,” the judge wrote.

She said Media Matters drew the ire of Trump world after it published an iffy report claiming that tech billionaire Elon Musk’s social media platform — at the time Twitter, now known as X — was placing ads from major firms next to antisemitic posts.

That sparked investigations by GOP-led states and eventually action by the FTC and new Chairman Andrew Ferguson. The FTC announced what’s known as a Civil Investigative Demand, or CID, calling for answers from the outlet about its reporting methods, its work on Mr. Musk’s platform and its financial statements.

The FTC said it wanted to see if Media Matters was helping gin up advertiser boycotts that have targeted outlets seen as conservative.

Judge Sooknanan called the FTC’s investigative demand “a retaliatory act.”

“Given the comments by Chairman Ferguson and his colleagues about Media Matters, the timing of the CID, and evidence of pretext, Media Matters is likely to show that retaliatory animus was the but-for cause of the FTC’s CID,” she concluded.

The Trump administration had argued the district court had no jurisdiction over the case and Media Matters didn’t have a viable cause of action to sue.

Judge Sooknanan rejected those defenses.

In her order, she shut down the civil investigative demand process the FTC launched against Media Matters.

Media Matters had told Judge Sooknanan that the FTC investigation had caused it to be gun-shy about some of its reporting on the Trump administration.

Media Matters’ initial 2023 report about advertising on Mr. Musk’s platform has sparked a wave of litigation and put enormous pressure on the liberal outlet.

Blaming the legal onslaught, Media Matters announced layoffs in May. The New York Times last month reported that the outlet was piling up legal bills.

• Stephen Dinan can be reached at sdinan@washingtontimes.com.