It’s tempting to ignore Trump’s outbursts, but there are some that represent patterns so troubling we really can’t afford to. PHOTOGRAPH BY THOS ROBINSON / GETTY

Last week, a judge hearing the lawsuit against Trump University ordered testimony unsealed that contained damning assessments from former employees of the now defunct enterprise. Trump University was a “fraudulent scheme,” a former sales manager said, that “preyed upon the elderly and uneducated to separate them from their money.” Trump responded with his usual dignity, maturity, and dedication to American ideals of fair play: he suggested that the judge must be against him because he was “Mexican.”

It’s tempting to ignore some of Trump’s outbursts, as a parent picking battles with an out-of-control eight-year-old might do, but there are some that represent patterns so troubling we really can’t afford to. And this is one of them: the vague—and, as it happens, false—imputation of foreign birth to people who criticize him or thwart his will in any way, as though ethnic difference was itself a smear that need only be hinted at to do its damage. At a campaign rally in San Diego last week, Trump declared, “The judge, who happens to be, we believe, Mexican, which is great, I think that’s fine. You know what? I think the Mexicans are going to end up loving Donald Trump when I give all these jobs, O.K.?” Notice that “we,” which implies a movement of ethnic purists training a beady eye on foreign elements, and then the incoherent and abrupt Trumpian shift to an assertion of how much he—third person—is loved by “the Mexicans.” Then he got threatening about the judge in the case, whose name is Gonzalo Curiel, in a straight-up thuggish way: “They ought to look into Judge Curiel, because what Judge Curiel is doing is a total disgrace. O.K.? But we will come back in November. Wouldn’t that be wild if I am President and come back and do a civil case? Where everybody likes it.” Trump kept this going all week—not only in the hopped-up atmosphere of a rally, but in an interview with the Wall Street Journal in which he said that Judge Curiel should recuse himself from the case.

Here, for those who might care about them, are the facts: Curiel was born in East Chicago, Indiana, in 1953 and attended Indiana University Law School. He is the son of Mexican immigrants. A 2002 Times article credits coöperation between Curiel and his counterparts across the border with bringing down the murderous Mexican cocaine cartel headed by Benjamín Arellano Félix. Investigators and prosecutors from San Diego and Tijuana agreed that the fact that they could speak to each other in Spanish, without interpreters and with some common frame of reference, helped enormously. According to the Washington Post, Curiel “gained acclaim prosecuting drug traffickers along the Tijuana corridor and was reportedly targeted for assassination by the Felix cartel.”

This is not, of course, the first time that Trump has dealt in nativist innuendo. It’s worth remembering that he was the leading public face of the birther canard—the claim that Barack Obama was not born in Hawaii, as his birth certificate proves, but in Kenya. Back in 2011, Trump took many, many opportunities to riff surreally on this made-up notion. To wit: "I have a birth certificate. People have birth certificates. He doesn't have a birth certificate. He may have one, but there is something on that birth certificate—maybe religion, maybe it says he's a Muslim, I don't know. Maybe he doesn't want that. Or he may not have one." Of course, if Obama had not been born on American soil, he would not have been eligible to be President. Obama, it should be said, had from the beginning produced a basic birth certificate, along with a contemporary birth announcement in a Hawaiian newspaper. And some birthers appeared to retreat when Hawaii released his “long-form” birth certificate, in 2011. But nailing down what happened at Kapiolani Maternity and Gynecological Hospital in 1961 was never really the point for Trump. The point was to feed religious and racial prejudice. Trump has never renounced these falsities or apologized for spreading them. When Chris Matthews pressed him on the matter at one of the Republican debates, he finally said, “I don’t talk about that anymore.” That’s not enough. In December, Trump was introduced at a rally by Joe Arpaio, the sheriff of Maricopa County, Arizona, who acknowledged him as a fellow birther: “We have something in common—the birth-certificate investigation, which is still going on." Trump did not disagree.

Back in 2011, after the release of the long-form certificate, President Obama did a number on Trump at the White House Correspondents' Dinner: “Now, I know that he’s taken some flak lately, but no one is happier, no one is prouder to put this birth-certificate matter to rest than the Donald. And that’s because he can finally get back to focussing on the issues that matter—like, did we fake the moon landing? What really happened in Roswell? And where are Biggie and Tupac?” That was when it was still possible to laugh at Trump’s obsessions without worrying that he might actually have a chance to impose them on the country. Last month, at his first press conference after Trump became the presumptive Republican nominee, President Obama said this: “We are in serious times, and this is a really serious job. This is not entertainment. This is not a reality show. This is a contest for the Presidency of the United States.” One of the hardest things about this election is that Donald Trump just isn’t funny anymore.