The Justice Department says it wants to add the question to aid its defense of Section 2 of the Voting Rights Act (which prevents the dilution of minority populations so their power cannot be weakened).

Supporters of adding the question say it shouldn’t be a problem because the citizenship question has since 2000 been asked on a smaller, recurring census-sponsored survey, the American Community Survey, and because the anonymity protections are strong. But the trouble is that today, everything even remotely political has become a battle over what it means to be an American.

Responding to both the census and the A.C.S. is the law of the land — you must do it or you could be fined. The data collected determines how a lot of money is allocated, as well as the allocation of House seats (and therefore Electoral College votes).

The more people who fail to respond, the more concern there is that we are missing some groups of people more than others, and that the failure to return the form among these group members is not random.

The government dedicates tremendous resources to reminding people to return their census form and even sends people to the doors of households from which no form has been filed. Mostly, it gets results. But if the reason for not filling it out is distrust of government, additional efforts at compliance by government might fall flat.