The high court did not say the question could not be asked, just that the administration's current justification for adding the question was insufficient.
On the court's final day of decisions before a summer break, the justices dealt blows to efforts to combat the drawing of electoral districts for partisan gain and put a hold on a Trump administration effort to add a citizenship question to the 2020 census.
The 4th Circuit Court of Appeals' decision comes a day after U.S. District Judge George Hazel of Maryland suggested in an opinion that racial discrimination and partisan power plays could be the underlying motives in asking everyone in the country about citizenship status.
A request from the Census Bureau to ask everyone in the country about citizenship status has set off litigation and debate and raised some important questions.
That technology — known as geographic information system, or GIS — uses computers to analyze neighborhoods, land formations, rivers and other data captured by satellites or traditional mapping.
The filing in Manhattan federal court said the discovery of new documents revealed that Thomas Hofeller contributed vital language to a letter used to justify adding a citizenship question to the 2020 census.
There appeared to be a clear divide between the court's liberal and conservative justices in arguments in a case that could affect how many seats states have in the House of Representatives and their share of federal dollars over the next 10 years.
The citizenship question has not been asked on the census form sent to every American household since 1950, and the administration’s desire to add it is now rife with political implications and partisan division.
The Citizenship question for the 2020 census has been hotly contested, as some say it will depress response rates from immigrant populations in the U.S.