The purpose of the census is to determine representation in the US House, and by extension electoral votes. Experts on the matter (including the Census Bureau itself) have reason to believe that questions like the citizenship question are intimidating to immigrants, even if they are legal, as well as to minorities in general. As such they are generally under-counted and their political influence is weakened. This is an especially big deal in states like Texas, Florida, Arizona, California and New York, which might lose seats if the minority/immigrant votes are under counted.

Yes, there is a concern it can be used against them. Nazi Germany used government data to find the Jews and people of other other ethnicities.

For most of my life I haven’t answered questions asking my religion. Only recently have I answered at hospitals when asked, and I’m still unsure when I do it, because of how I was raised. My husband does answer he is Hispanic, but even on that I sometimes think it might be better to leave that all blank.

It wasn’t just “insufficient justification” it was also that the administration was disingenuous in their reason for asking the question.

There is definitive evidence that the question was intended to cause under-counting of immigrants regardless of legal status.

Remember, when the Constitution was written and the diennial enumeration established, it was to count everyone, citizen or not. And many non-citizens who would never be permitted to vote were counted, including slaves, native Americans, women, Asians.

As @zenvelo stated there is evidence the question and answers had other uses than just data collection.
They could, and most likely would, be used to gerrymander districts.

“Asking census respondents whether they are US citizens “would clearly be a disadvantage to the Democrats” and “advantageous to Republicans and Non-Hispanic Whites”, wrote Tom Hofeller, the mastermind behind the effort and an expert on redistricting for the Republican National Committee.

Hoeffler, who died last year, reportedly analyzed Texas state legislative districts for the conservative news outlet the Washington Free Beacon in 2015, to determine how drawing those districts based on citizenship would impact the vote.

He concluded that doing so would be a “radical departure from the federal ‘one person, one vote’ rule presently in the United States”. He said that it would reduce representation for Hispanics — who tend to vote Democrat — while boosting representation for white Republicans.”

If one person, one vote was an issue, then how could John Roberts vote against the citizenship question but not vote against gerrymandering?

This is a lot of noise about nothing. Citizenship has been a standard question in the past and would provide good information about the make up of the country. Nobody knows how many illegals or simply non-citizens are in the country and it seems like something we should know. The census provides a lot more information than just how many people are here.

The court sent this back because there was new information and the SCOTUS in not a fact finding court. it is a constitutional court.

@Jaxk Why would would people without papers answer the census at all? Already I’m guessing many of them don’t answer out of fear of being found even without the citizenship question. I’m not sure it makes a difference to know people are citizens or not?

People who are legal in the country, but not citizens would be answering “no” to a citizenship question, but surely you would agree they should count for districting of representatives? Or, don’t you?

I find the whole thing a scam. We ask what nationality people are, we ask what sex they are, we ask how old they are, we ask how many children they have, marital status and many, many other questions. So why is citizenship such a bad question? Are we afraid we might actually find out how many illegal immigrants live in this country?

It is bad only because the “Storm Troopers” may come to their door like in Nazi Germany; when they put “Star of David” patches on all the Jews.

If I were here illegally, I don’t think I would answer the citizenship question honestly.

@jca2. It is more about, “would you even participate in the census, or would you avoid being counted?”

@zenvelo: If I were illegal, I wouldn’t participate in it.

That is precisely the point. And it is invariably those who profess no confidence in the government when it comes to intrusion in their lives who now see no problem with a question, the answer to which on its face can clearly be utilized in the prosecution of the respondent. It is a flag so red to anyone hiding from the government that its inclusion all but guarantees a significant undercount of not merely the undocumented, but those here with legitimate visas. Why provide the government the information with which you can be hounded?