A president has broad powers over immigration under the Constitution and federal laws, but they are not unlimited. At the very least, there must be a reasonable basis for restrictions on immigration. None exists for President Trump’s threat to temporarily ban all immigrant visa admissions to the United States.

As with earlier, problematic immigration policies like the entry ban aimed at several predominantly Muslim countries, this proposal started out with a remarkably broad promise by the president: a ban on all immigration. That sweeping rhetoric has a cost of its own. Among other things, it may discourage international students from enrolling in American universities this fall, and otherwise signal “keep out” to visitors who would actually boost the economy. But beyond the rhetorical overkill, there are other problems with this ban. The actual policy proposal is much less than promised by tweet, but even in its whittled down form, it is still unlawful.

A ban on the entry of individuals who have been granted immigrant visas would not affect as many people as you might think. Although there are usually more than 180 million entries into the United States every year, most of that traffic is by people holding temporary visas. This policy would affect only those immigrants who have been authorized for permanent residency. That involves less than a million people — a number that has declined in recent years because of other entry bans, new requirements on immigrants and slow visa processing. The answer to the crushing domestic unemployment crisis caused by the coronavirus outbreak is clearly not going to be found in a ban on these immigrants.