George J. Borjas is a professor of economics and social policy at the Harvard Kennedy School. This article from has been adapted from an essay previously published on his blog.

In his major foreign policy speech earlier this week, Donald Trump explained how he would expand the “ideological” vetting of immigrants who want to come to the United States. “The time is overdue to develop a new screening test for the threats we face today,” he said. “I call it extreme vetting.” In particular, Trump proposed, “We must also screen out any who have hostile attitudes towards our country or its principles—or who believe that Sharia law should supplant American law. Those who do not believe in our Constitution, or who support bigotry and hatred, will not be admitted for immigration into the country.”

As with practically all of Trump’s policy statements, the over-the-top commentary came swiftly. Over at the Washington Post an opinionator opined (and I’m only slightly paraphrasing) that Trump’s ideas were crazier than crazy. I knew it wouldn’t take long before somebody called them un-American, and MSNBC nicely obliged; a commentator commented that “this is the single most un-American thing I have ever heard in my life.”


If all those pundits had bothered to do just a couple of minutes of googling before reacting, they would have discovered that immigrant vetting, and even extreme immigrant vetting, has a very long tradition in American history. Since before the founding even, U.S. policies about whom the country chooses to welcome and reject have changed in response to changing conditions. As early as 1645, the Massachusetts Bay Colony prohibited the entry of poor or indigent persons. By the early 20th century, the country was filtering out people who had “undesirable” traits, such as epileptics, alcoholics and polygamists. Today, the naturalization oath demands that immigrants renounce allegiance to any foreign state. Even our Favorite Founding Father du jour, Alexander Hamilton (himself an immigrant), thought it was important to scrutinize whoever came to the United States. He wrote:

To admit foreigners indiscriminately to the rights of citizens, the moment they put foot in our country … would be nothing less, than to admit the Grecian Horse into the Citadel of our Liberty and Sovereignty. … The United States have already felt the evils of incorporating a large number of foreigners into their national mass. … In times of great public danger there is always a numerous body of men, of whom there may be just grounds of distrust; the suspicion alone weakens the strength of the nation, but their force may be actually employed in assisting an invader.

In other words, immigration vetting is as American as apple pie.

In the colonial era, governments were particularly concerned with the entry of “public charges” who could impart substantial costs on the indigenous population. In 1691, the Province of New York must have hired a professional economist to design a bonding system that would discourage the entry of people who would be a drag on public resources:

All Persons that shall come to inhabit within this Province ... and hath not a visible Estate, or hath not a manual occupation, shall, before he be admitted an Inhabitant, give sufficient surety, That he shall not be a burden or Charge to the respective places, he shall come to Inhabit. Which Security shall continue for two years.

And in 1740, Delaware enacted legislation to “Prevent Poor and Impotent Persons being Imported." Many of these colonial-era restrictions remained in place until 1875, when the Supreme Court invalidated state-imposed head taxes on immigrants to fund the financial burden of caring for poor entrants, and made immigration the sole purview of the federal government. But that wasn’t the end of immigrant filters. Congress responded by creating the vetting system that—although modified many times—remains in place today. In 1875, Congress prohibited the entry of prostitutes and convicts. In 1882, Congress suspended the immigration of Chinese laborers, and added idiots, lunatics and persons likely to become public charges to the list for good measure.

One of my favorite examples of the extreme vetting is the 1917 Immigration Act, which, in addition to effectively barring immigration from Asia, listed the many traits that would make potential immigrants inadmissible. The following quote is very long, but it shows the excruciating detail with which Americans have historically resorted to extreme vetting:

All idiots, imbeciles, feeble-minded persons, epileptics, insane persons; persons who have had one or more attacks of insanity at any time previously; persons of constitutional psychopathic inferiority; persons with chronic alcoholism; paupers; professional beggars; vagrants; persons afflicted with tuberculosis in any form or with a loathsome or dangerous contagious disease; persons not comprehended within any of the foregoing excluded classes who are found to be and are certified by the examining surgeon as being mentally or physically defective, such physical defect being of a nature which may affect the ability of such alien to earn a living; persons who have been convicted of or admit having committed a felony or other crime or misdemeanor involving moral turpitude; polygamists, or persons who practice polygamy or believe in or advocate the practice of polygamy; anarchists, or persons who believe in or advocate the overthrow by force or violence of the Government of the United States, or of all forms of law, or who disbelieve in or are opposed to organized government, or who advocate the assassination of public officials, or who advocate or teach the unlawful destruction of property; persons who are members of or affiliated with any organization entertaining and teaching disbelief in or opposition to organized government, or who advocate or teach the duty, necessity, or propriety of the unlawful assaulting or killing of any officer or officers ... of the Government of the United States or of any other organized government.

In other words, even a century ago we had put in place ideological filters against anarchists, persons who advocate the destruction of property, and persons who believe in overthrowing the government of the United States.

Of course, some of these filters, such as those restricting the entry of epileptics or Asians, have long since been rolled back—and for good reason. But many of them—especially those pertaining to criminals, and people who are likely to work against U.S. interests—remain in current law, with additions that reflect the changing security landscape. Hijacking and drug trafficking, for example, became major concerns only in the past few decades, and the law changed accordingly to ensure that it became more difficult for hijackers and drug traffickers to enter the country.

Here is the application filled out by green card applicants today (Form I-485). Among the many questions are:

Have you EVER, in or outside the United States:

a. Knowingly committed any crime of moral turpitude or a drug-related offense for which you have not been arrested?

Have you EVER:

a. Within the past 10 years been a prostitute or procured anyone for prostitution, or intend to engage in such activities in the future?

b. Engaged in any unlawful commercialized vice, including, but not limited to, illegal gambling

c. Knowingly encouraged, induced, assisted, abetted or aided any alien to try to enter the U.S. illegally?

d. Illicitly trafficked in any controlled substance, or knowingly assisted, abetted, or colluded in the illicit trafficking of any controlled substance?

Have you EVER engaged in, conspired to engage in, or do you intend to engage in, or have you ever solicited membership or funds for, or have you through any means ever assisted or provided any type of material support to any person or organization that has ever engaged or conspired to engage in sabotage, kidnapping, political assassination, hijacking, or any other form of terrorist activity?

Do you intend to engage in the United States in:

a. Espionage?

b. Any activity a purpose of which is opposition to, or the control or overthrow of, the Government of the United States, by force, violence, or other unlawful means?

Have you EVER been a member of, or in any way affiliated with, the Communist Party or any other totalitarian party?

Did you, during the period from March 23, 1933 to May 8, 1945, in association with either the Nazi Government of Germany or any organization or government associated or allied with the Nazi Government of Germany, ever order, incite, assist, or otherwise participate in the persecution of any person because of race, religion, national origin, or political opinion?

And, finally, here’s part of the oath that immigrants who wish to become citizens of the United States must recite at the naturalization ceremony:

I hereby declare, on oath, that I absolutely and entirely renounce and abjure all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty; … that I will support and defend the Constitution and laws of the United States of America against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I will bear arms on behalf of the United States when required by the law.

In view of this almost 400-year track record, is it really that big a stretch to add questions, as Trump proposes, that would expand the filtering to reflect political conditions and national security concerns today? In particular, is it really that big a departure from what we have done in the past if we also asked green card applicants: “Do you believe that religious law should supplant the Constitution of the United States?” Or if we asked: “Do you believe that the law should treat people differentially based on their gender, their race, or their sexual orientation?” And would it really be that unreasonable if we had second thoughts about admitting persons who answered those questions in the affirmative? Are there really that many Americans who would disagree with the notion that a reasonable immigration policy should, in Trump’s words, keep out “those who do not believe in our Constitution, or who support bigotry and hatred”?

Of course, it is sensible to wonder whether such filters are effective. I doubt that the 9/11 terrorists admitted in their applications for foreign student visas that they planned to use their flight training to fly planes into the World Trade Center. But the fact that such filtering is far from perfect does not imply that we should not have any filters whatsoever. If nothing else, the perjury in the visa application gives the government an easy way for detaining and deporting dangerous immigrants living in our midst, even after they become American citizens. The falsification or concealment of relevant facts during the application process provides grounds for the removal of a green card, for the revoking of naturalization, and for eventual deportation.

The many filters that have been used throughout American history to determine who will and will not get an entry visa have an obvious purpose. Yes, some of them, in the hindsight of history, seemed to have had no constructive purpose. But for the most part, they helped to strengthen the social and political fabric of our country and they helped to define the common set of values that distinguishes us as Americans. Or to quote Alexander Hamilton again: “The safety of a republic depends essentially on the energy of a common National sentiment; on a uniformity of principles and habits.”

So, regardless of what you think about the Trump candidacy, the next time you hear that Trump’s proposal for immigrant vetting is un-American, the correct response is that it is American to its core. And the next time you hear that Trump’s proposal is crazier than crazy, the correct response is that—given the mess the world is in—it is the notion that we should not vet immigrants more carefully that is certifiably insane.