The immigration debate in America is often framed in absolutes: Those who want the law enforced, support the construction of a wall along the southern border, or are concerned about vetting migrants from troubled parts of the world are denounced as racist, xenophobic bigots. As a former foreign service officer who screened more than 10,000 visa applications, I’ve seen firsthand why tough immigration enforcement is necessary.

The question I hear most frequently regarding my time as an immigration gatekeeper is: Why can’t we...