“You’re going to have a deportation force.”

 — Donald Trump, Nov. 11

As you heard again during Tuesday’s GOP primary debate, Donald Trump has as a policy goal turning the United States into a police state to facilitate the mass roundup of around 11 million men, women and children who are living in the country unlawfully. He wants to expel them from our borders via a “deportation force.”

His faith in the ability of government to execute this policy — granted, under his tremendous leadership — is (please pardon the repetition) tremendous. It must be said clearly that his plan is morally awful.

[After the debate: What the candidates said and where they go from here]

Does he understand how his police state would affect the country? Apart from the obvious ways that have been much discussed — breaking up families; a massive disruption for businesses, schools, churches, communities; potentially turning neighbor against neighbor — Trump’s powerful Department of Homeland Security would almost surely end up mistakenly apprehending and detaining U.S. citizens. And probably deporting some of them, too.

The Trump immigration plan’s effect on U.S. citizens has received much less attention than the effects I just mentioned. So let’s discuss it.

How many American citizens are we talking about? After doing some digging, I’ve discovered (unsurprisingly) that it’s very difficult to find good estimates of how many U.S. citizens we would expect to be detained or deported under Trump’s plan. And any estimates generated by today’s data would likely not apply to Trump’s police state.

Why? If the rate at which U.S. citizens are incorrectly rounded up increases as the overall number of apprehensions increases, today’s estimates of the error rate would be too low to apply to the Trumptopia. Trump has said that he will remove all undocumented immigrants from the country “so fast that your head will spin” — specifically, in under two years. It’s hard to imagine that pace allowing for the careful deportation hearings that might significantly lower the rate at which U.S. citizens are incorrectly deported, or allowing for care to be taken not to mistakenly detain U.S. citizens in the first place. It’s much easier to imagine that pace requiring significantly more troubling, blunt methods — predicting a police state is entirely reasonable — that would be much more prone to mistakes. This timetable also drains credibility from Trump’s promise that his deportation force would go about their business humanely.

So let’s make an educated guess. Based on a 2011 paper by Northwestern University professor Jacqueline Stevens and a 2011 report from the University of California, Berkeley’s law school, let’s say that about 1 percent of total apprehensions are in error because the person apprehended is a U.S. citizen. (Remember, these estimates are based on today’s data.) One percent of 11 million implies over 100,000 U.S. citizens mistakenly apprehended, some of whom may end up deported. That’s a lot of people. It eclipses in number the internment of U.S. citizens of Japanese ancestry during World War II.

Say instead the error rate is 0.1 percent; a rate likely much lower than it would be in reality, despite Trump’s promises of “really good management.” That’s still thousands of people. Thousands of U.S. citizens apprehended by a police state — men, women and children who are guaranteed the protections of the Constitution.

Look, illegal immigration is a hard and serious issue. There are a range of intelligent, informed, serious proposals to address the issue over which reasonable people of good faith can disagree. And then there’s Donald Trump and his plan.

Of course, any program will have an error rate, and our current programs do as well. Inevitable error is not necessarily a reason to stop a program of apprehending and deporting immigrants unlawfully living and working in the United States. But the magnitude of Trump’s plan means that even a tiny error rate will cause massive damage.

Can Trump get that error rate sufficiently low? Conservatives, who have a healthy distrust of the government’s ability to run complicated programs well, should be very dubious. Conservatives, who cherish the Constitution, should be apoplectic about a policy that would spit in the face of that document’s understanding of the relationship between citizen and government.

Conservatives should be appalled by the implications of Trump’s signature policy — because of what his deportation force might accidentally do to U.S. citizens. And because of what it is designed to do to illegal immigrants and their families, the communities in which they live, and the character of the nation.