Commerce Secretary Wilbur Ross. (Marcos Brindicci/Reuters)

J. Richard Cohen is president of the Southern Poverty Law Center. SPLC lawyers were among those who litigated the case challenging Alabama’s Taxpayer and Citizen Protection Act.

Common sense tells you that adding a question to the 2020 Census asking about citizenship status will depress response rates from an immigrant community already traumatized by President Trump’s incendiary rhetoric and deportation machinery. But common sense was not enough for the Trump administration.

Certainly, it was not enough for Commerce Secretary Wilbur Ross, whose department is responsible for administering the census and who has bowed to pressure from the Justice Department to include a citizenship question. Refusing to acknowledge the question’s predictable impact, Ross has instead insisted that “no one [has] provided evidence that reinstating a citizenship question on the decennial census would materially decrease response rates.”

This is a bizarre claim, as it’s the responsibility of the Commerce Department to determine whether proposed questions will promote or interfere with the constitutionally required census. And doing so would have been easy in this case: All Ross had to do was to look to Alabama’s experience with citizenship questions.

In 2011, Alabama passed the Alabama Taxpayer and Citizen Protection Act, better known as HB 56. The law was designed to make life so difficult for undocumented immigrants and their family members, documented or not, that they would “deport themselves” from Alabama. It was written in large part by Kris Kobach, the Kansas secretary of state who had earlier drafted another anti- ­immigrant law in Arizona and who would later pitch a census citizenship question to Trump at the start of his administration.

One of the goals of the Alabama law was to “measure and assess the population of [Alabama] students who are aliens not lawfully present.” This meant requiring schools to ask parents or guardians of students to submit their children’s birth certificates or to notify the schools, under penalty of perjury, of their children’s “actual citizenship or immigration status” when enrolling them. In short, Alabama law instructed the state’s schools to ask a citizenship question.

Undocumented students have a constitutional right to enroll in public schools, and Alabama claimed that it was simply trying to count them. But the impact of the Alabama citizenship question was both immediate and devastating.

Even though the law did not apply to students who were already enrolled, 2,285 Hispanic students — about 7 percent of the statewide total — were “absent” from schools across the state on the first Monday after the law went into effect, according to state education officials. In one small Alabama town, the New York Times reported, more than 100 Hispanic students withdrew from school altogether within the first week. One mother told the Southern Poverty Law Center that she kept her children out of school for two weeks, fearing they would be singled out for harassment. “My kids told me there were no [other] Hispanics at the school, so I didn’t let them go,” she said.

Recognizing that Alabama’s effort to question families about the immigration status of their children would deter many from sending their children to school, a federal appellate court ruled the law unconstitutional.

The likely impact of a citizenship question on the census would surely be far more profound. Consider the situation of an undocumented mother with two children who are citizens born in this country. She remembers Trump’s anti- ­immigrant rhetoric on the campaign trail. She has read about or may even know families who have been ripped apart when one family member was swept up in an immigration raid.

Now ask yourself: If you were that mother and received a census form from the Trump administration asking about your citizenship, would you answer the question and mail the form back, trusting the administration not to use the information against you? Or would you play it safe and ignore it?

Given that we cannot depend on Ross’s common sense, his courage to stand up to pressure from the Justice Department or his willingness to assess the impact of the citizenship question on the integrity of the census, our best hope is that the courts will block the Trump administration from asking the citizenship question, just as the courts blocked Alabama from asking questions about the citizenship of its students.

Like the right of all students to enroll in public schools, the accuracy of the census is a matter of great constitutional significance because it determines the distribution of the 435 members of the U.S. House of Representatives across the states for a decade. It also is a matter of tremendous practical significance because it determines, among other things, the distribution of hundreds of billions of dollars in federal funds each year.

There is no place for a question that will deter some people from participating in the census. The stakes for our democracy are simply too high.