Andrew Napolitano was a Superior Court judge in New Jersey until, frustrated by the constraints of his salary, he left the bench for more lucrative pastures: talk radio, a syndicated small-claims court TV series (“Power of Attorney”) and, eventually, Fox News, where he rose to become the network’s senior legal analyst.
It was in that basic-cable capacity this week that Mr. Napolitano managed to set off a cascading scandal, which by Friday had sparked a trans-Atlantic tiff between Britain and the United States while plunging President Trump’s close relationship with Fox News into new, murkier territory.
It was new ground for Mr. Napolitano, 66, who prefers being addressed as “The Judge” and once insisted that Fox News install bookshelves and wood-paneling in his newsroom office, the better to resemble a judge’s chambers.
But Mr. Napolitano’s unlikely leap into global politics can be explained by his friendship with Mr. Trump, whom he met with this year to discuss potential Supreme Court nominees. Mr. Napolitano also has a taste for conspiracy theories, which led him to Larry C. Johnson, a former intelligence officer best known for spreading a hoax about Michelle Obama.
Let’s back up. The saga began on Tuesday on “Fox & Friends,” the chummy morning show, where Mr. Napolitano made a bizarre and unsupported accusation: Citing three unnamed sources, he said that Britain’s top spy agency had wiretapped Mr. Trump on behalf of President Barack Obama during last year’s campaign.
Cable news blather, especially at that hour, usually vanishes at the commercial break. But on Thursday, Mr. Trump’s press secretary, Sean Spicer, repeated the claim from the White House podium, infuriating British officials.
On Friday, Fox News was forced to disavow Mr. Napolitano’s remarks. “Fox News cannot confirm Judge Napolitano’s commentary,” the anchor Shepard Smith said on-air. “Fox News knows of no evidence of any kind that the now-president of the United States was surveilled at any time, any way. Full stop.”
The terse declaration boosted the credibility of Fox News’s newsroom, which is often attacked as biased, but also put it in the awkward position of repudiating one of its featured contributors. And it could threaten the cozy dynamic between Mr. Trump, a frequent Fox viewer, and the network’s conservative hosts.
Tucker Carlson, Sean Hannity and the prankster Jesse Watters are among the few television personalities to be granted one-on-one interviews with the president. Programs like “Fox & Friends” often serve as cheerleaders for him, and the network is increasing its focus on hard-line conservatism: A new weekly series, hosted by a leader of the Brexit movement, Steve Hilton, will focus on right-wing populism.
Mr. Napolitano, who keeps a residence in Manhattan at Trump International Hotel & Tower on Central Park West, did not respond to inquiries on Friday.
But Mr. Johnson, who was himself once a Fox News contributor, said in a telephone interview that Mr. Napolitano called him on Friday and requested that he speak to The New York Times. Mr. Johnson said he was one of the sources for Mr. Napolitano’s claim about British intelligence.
Mr. Johnson became infamous in political circles after he spread false rumors in 2008 that Michelle Obama had been videotaped using a slur against Caucasians. In the interview on Friday, Mr. Johnson acknowledged his notoriety, but said that his knowledge of surveillance of Mr. Trump came from sources in the American intelligence community. Mr. Napolitano, he said, heard about his information through an intermediary.
“It sounds like a Frederick Forsythe novel,” Mr. Johnson said.
Mr. Trump refused to back down from the claims on Friday, and even praised Mr. Napolitano, telling reporters, “All we did was quote a very talented legal mind.”
The president’s next scheduled appearance on Fox News is Saturday night, when an interview will air between him and Mr. Watters, a host known for on-the-street interviews that have been denounced as offensive and, at times, racist.
In a clip released on Friday, Mr. Watters asks Mr. Trump which celebrity he would most like to fire: Alec Baldwin, Senator Chuck Schumer or CNN’s president, Jeff Zucker.
“I don’t want to say,” Mr. Trump replied. “But I will say I’m disappointed in all three.”