President Trump’s border czar, Tom Homan, is planning to enforce the law on businesses employing people without authorization to work in America. While much attention is focusing on deportation, worksite enforcement promises to address the demand that incentivizes migration.

Mr. Homan, acting director of the U.S. Immigration and Customs Enforcement, or ICE, in Trump’s first term, is emerging as the face of the second administration’s border policies. Where others sling harsh invective at non-citizens, he stakes out a position defending them against exploitation.

On Wednesday, Mr. Homan was asked by CNN’s Kaitlin Collins about the “massive impact” of deportation on the construction, agriculture, and hospitality industries. “Let’s remember,” he responded, “it’s illegal to hire an illegal alien.”

Mr. Homan said that employers hire people under the table because “they can work them harder, pay them less, and undercut their competition who has U.S. citizen employees.” He said he finds “most victims of trafficking, sex trafficking, and forced labor” at work sites, because they don’t fear the law.

“If we’re serious about human trafficking,” Mr. Homan said, “both forced labor and forced sex trafficking, that’s where we find the victims. That’s where we save the victims. So, worksite enforcement is coming back in a big way.”

This approach flips the script about border security in general and the Trump Administration in particular. Rather than being yet another person persecuting those who cross the border in search of work, he hammers the point that they pay the stiffest price for lax enforcement of laws.

Mr. Homan started as a Border Patrol Agent in 1984, and President Obama appointed him as the executive associate director of enforcement and removal operations in 2013. These experiences gave Mr. Homan a wealth of first-hand experience that illuminated the facet of the cruel status quo.

Two weeks ago, on “Dr. Phil Primetime,” Mr. Homan was asked, “Why is this so important to you?” He gave emotional accounts of the suffering that results from a porous border and failure to address the supply side that incentivizes people to try their luck sneaking into America.

Mr. Homan said he “wore the uniform” as “an ICE agent” and “first ICE director,” and came up “through the ranks.” His descriptions of “the tragedies” he has witnessed are stark. “I’ve talked to young girls as young as nine,” he said, “that were raped multiple times by members of the cartel.”

Choking up, Mr. Homan said, “You get on your knees and talk to a little girl that had everything innocent and pure ripped from her — she’ll never be the same — it moves you.” He recounted standing “in the back of a tractor trailer” with 19 dead “at his feet, including a five-year-old little boy.”

Those people, Mr. Homan said, were “in their underwear because they were baking to death. They died in that steel box.” That atrocity, in 2011, occurred at Victoria, Texas, and resulted in a 34-year sentence for the truck’s driver.

Mr. Homan described testifying to the House Committee on Oversight and Accountability in 2019 about the incident. “One congressman,” he recalled, “said I didn’t care about dying children unless they’re white,” and earned a stinging rebuke.

“I stood there and knelt beside that five-year-old boy,” Mr. Homan said, repeating his response to the congressman, “and put my hands on him and said a prayer for him because I knew what the last hour of his life was like. No one deserves to die that way, especially children.”

Mr. Homan said that he’d “held many” of the dying and dead “and talked to a lot of women and children that were sexually assaulted. “It all could be prevented,” he said, “if we secure the border. Securing the border saves lives.”

In a Reuters/Ipsos poll last week, 53 percent of Americans said that “all immigrants in the U.S. illegally should be deported,” compared to 14 percent who think they should stay. Because of the emotions involved, just applying the law — a cornerstone of equal protection — is often cast as cruelty.

Expect Mr. Homan to make a counterappeal to the heart: Allowing human traffickers, cartels, and employers to profit off misery costs lives. It’s a plea for compassion born from 40 years of experience, and an argument that won’t be easy for detractors to demonize or dismiss.