When it comes to the White House’s apparently new policy of branding any and all illegal immigrants as per se “criminals,” these columns are reminded of Mayor Giuliani’s assessment in 2007 during his ill-starred presidential bid. “It’s not a crime,” Mr. Giuliani explained when illegal immigration came up as a topic on the campaign trail. “I know that’s very hard for people to understand, but it’s not a federal crime.”

That view contrasts with the claim put forward Tuesday by Mr. Trump’s press secretary, Karoline Leavitt, who, was asked by a reporter, “how many of the 3,500 immigrants arrested since Trump took office have criminal records,” as Axios puts it. “All of them,” Ms. Leavitt replied, “because they illegally broke our nation’s laws.” Beyond that, the press secretary, Axios reports. “declined to say if all the undocumented immigrants had criminal records,” Axios reports.

Ms. Leavitt appeared to relish the idea that she was breaking new ground on this head. “I know the last administration didn’t see it that way,” she added, “so it’s a big culture shift in our nation to view someone who breaks our immigration laws as a criminal, but that’s exactly what they are.” Members of the left-leaning press didn’t seem convinced, more or less aping Tom Sawyer’s insistence to Huck Finn that “YOUR saying so don’t make it so.”

We remember Mr. Giuliani’s remarks  even though they emerged in a campaign trail interview with Glenn Beck back in ought seven. The former mayor invoked his experience as a federal prosecutor to establish his bona fides. “I was U.S. attorney in the Southern district of New York,” Mr. Giuliani harrumphed. “So believe me, I know this. In fact, when you throw an immigrant out of the country, it’s not a criminal proceeding. It’s a civil proceeding.”

Mr. Giuliani, too, advised against making illegal immigration a crime. “We couldn’t prosecute 12 million people. We have only 2 million people in jail right now for all the crimes that are committed in the country, 2.5 million.” So who has it right on the “criminal” question, Hizzoner or Ms. Leavitt? It’s something of a split decision. Federal law does make “improper entry” to America a crime — carrying the potential for both criminal and civil penalties. 

The Supreme Court, though, confirms Mr. Giuliani on deportation being largely a civil affair. In Padilla v. Kentucky, Justice John Paul Stevens noted that “we have long recognized that deportation is a particularly severe ‘penalty,’ but it is not, in a strict sense, a criminal sanction.” Yet even if “removal proceedings are civil in nature,” Stevens stated, “deportation is nevertheless intimately related to the criminal process.” Got it? It’s a draw.

In the event, Mr. Giuliani lost his bid for the GOP presidential nod to Senator McCain, no hard-liner on illegal immigration. The fact that migration was in 2008 a point of mild contention is a marker of how far the political climate has shifted. The wave of millions of illegal migrants since then has made voters determined. Mr. Trump’s vows to regain control of the border, and deport illegal migrants, certainly played a key part in his victory on Election Day. 

Now Mr. Trump is carrying out his campaign vows. Already debates have arisen within the MAGA movement as to how strict an approach to take on migration policies, like the H1-B employment visas that help tech firms fill their ranks. The Sun’s view on this debate is to stress the need to curb illegal migration, while widening the door to the legal migration that fuels growth. Mr. Trump appears to grasp the benefits of such an approach. 

The president is right that too many actual criminals lurk among illegal migrants. Deportation efforts rightly focus on such offenders. That doesn’t trump the fact that, as Mr. Trump says, “we need people.” So is it constructive to denigrate as criminals so many otherwise law-abiding migrants? That, in the long run, could prove to be a form of political malpractice reminiscent of Talleyrand’s famous quip: “It is worse than a crime, it is a mistake.”