WASHINGTON — A federal judge in Florida imposed sanctions Thursday against a group of lawyers for former President Donald Trump who handled a sprawling lawsuit that accused Hillary Rodham Clinton and a range of Trump's perceived enemies of a vast conspiracy against him.

The judge, Donald Middlebrooks of the Southern District of Florida, had thrown out the case in September, and in a scathing 19-page ruling, he accused Trump's lawyers of abusing the legal system by suing for political purposes in a case that he portrayed as full of misinformation. "Every claim was frivolous, most barred by settled, well-established existing law," he said.

The ruling comes as the ethics and conduct of a range of lawyers working for Trump are under scrutiny, including their baseless challenges over the legitimacy of the 2020 election and false statements assuring the Justice Department that Trump had returned all classified documents in his possession.

In the racketeering case, Middlebrooks, who was appointed by then-President Bill Clinton, wrote that Trump put forward "political grievances masquerading as legal claims." He added, "The courts are not intended for performative litigation for purposes of fundraising and political statements."

The Trump lawyers who must now pay a fine of $50,000 are Alina Habba, Michael Madaio, Peter Ticktin and Jamie Alan Sasson. In a statement, Habba said she planned to appeal the decision. The remaining lawyers did not immediately respond to a request for comment.

Trump's lawyers were also ordered to cover about $16,000 in legal fees paid by one of the defendants, Charles Dolan, a Democratic public-relations executive. The penalties issued Thursday may foreshadow things to come.

After the judge threw out the lawsuit, Dolan quickly filed a request for sanctions. But a large group of defendants in the case, including Hillary Clinton and the Democratic National Committee. separately filed a joint request for sanctions, which remains pending before the judge.

A lawyer for Dolan, George Doumar, praised the decision, saying lawsuits such as Trump's had undermined the legal system.

"We gave Trump's lawyers multiple warnings, and rather than serve as gatekeepers of the integrity of the court system, they doubled down on unsupported allegations," he said.

In filing the lawsuit in March, Trump named 31 people and organizations as defendants. The case amounted to yet another venue for Trump to air his grievances and conspiracy theories about the Russia investigation.

Dolan was the subject of pro-Trump conspiracy theories after John Durham, the Trump-era special counsel investigating the Russia investigation, mentioned him in an indictment of Igor Danchenko, a Russia analyst who gathered many of the claims in the so-called Steele dossier. (Danchenko was acquitted last month.)

The dossier is a now-discredited compendium of rumors about purported connections between Trump and Russia based on political opposition research that Democrats had indirectly funded. It included a notorious claim that Russian intelligence had a blackmail tape of Trump with prostitutes.

The indictment described how in the summer of 2016, when Danchenko visited Moscow, he met with Dolan, who had been staying at the hotel where the purported tape had supposedly been filmed. He also reportedly toured the suite where Trump had stayed.

Durham's indictment can be read as insinuating that Dolan might have been involved in the tape rumor. But Dolan said he had never heard the rumor until BuzzFeed published the dossier in January 2017, and the indictment did not say otherwise.

Trump's lawyers, however, accused Dolan of originating the rumor. They also accused Dolan of having conspired with Danchenko to create a dossier to "smear" Trump, while inaccurately describing him as a former chair of the DNC and a senior Clinton campaign official.

Dolan's lawyers asked that he be dropped from the case, saying their client knew nothing of the sex tape rumor, had not conspired with Danchenko to create a dossier and had never been chair of the DNC. His support for the Clinton campaign, they said, was limited to knocking on doors as a volunteer.

But Trump pressed on. After Middlebrooks dismissed the lawsuit and Dolan asked for sanctions, the Trump team claimed that "nearly all" of the allegations the lawsuit had made against him came from the Danchenko indictment.

That, Middlebrooks wrote, "is simply not so," saying Trump had instead "cherry-picked portions which supported his narrative while ignoring those that undermined or contradicted it."