Move raises questions as to what Trump administration seeks to do with the data and concerns among activists it could be misused

As the US supreme court weighs whether the Trump administration can ask people if they are citizens on the 2020 census, the Census Bureau is quietly seeking comprehensive information about the legal status of millions of immigrants.

Under a proposed plan, the Department of Homeland Security (DHS) would provide the bureau with a broad swath of personal data about noncitizens, including their immigration status, the Associated Press has learned. A pending agreement between the agencies has been in the works since at least January, the same month a federal judge in New York blocked the administration from adding the citizenship question to the 10-year survey.

On Wednesday, a federal judge in California also declared that adding the citizenship question to the census was unconstitutional, saying the move “threatens the very foundation of our democratic system”.

The data that homeland security would share with census officials would include noncitizens’ full names and addresses, birth dates and places, as well as social security numbers and highly sensitive alien registration numbers, according to a document signed by the Census Bureau and obtained by the AP.

Judge blocks White House plan to ask citizenship question on census Read more

Such a data dump would be apparently unprecedented and give the Census Bureau a view of immigrants’ citizenship status that is even more precise than what can be gathered in door-to-door canvassing, according to bureau research.

Six former census and DHS officials said they were not aware that individuals’ citizenship status had ever before been shared with the census. “Generally, the information kept in a system of records is presumed to be private and can’t be released unless it fits with a certain set of defined exceptions,” said Leon Rodriguez, who led the DHS agency responsible for citizenship under the Obama administration.

The move raises questions as to what the Trump administration seeks to do with the data and concerns among privacy and civil rights activists that it could be misused.

Census spokesman Michael Cook said the agreement was awaiting signatures at DHS, but that census expected it would be finalized “as soon as possible”.

“The US Census Bureau routinely enters into agreements to receive administrative records from many agencies, including our pending agreement with US Citizenship and Immigration Services, to assist us in our mission to provide quality statistics to the American public,” Cook said in a statement. “By law, the Census Bureau does not return any records to the Department of Homeland Security or any of its components, including Immigration and Customs Enforcement.”

Jessica Collins, a spokeswoman for Citizenship and Immigration Services, said no agreement had been finalized. She said the purpose of such agreements was to help improve the reliability of population estimates for the next census.

“The information is protected and safeguarded under applicable laws and will not be used for adjudicative or law enforcement purposes,” Collins said.

Civil rights groups accuse the White House of pursuing a citizenship question because it would discourage noncitizens from participating in the census and lead to less federal money and representation in Congress for states with large immigrant populations. Census researchers say including the question could yield significant underreporting for immigrants and communities of color.

Under the pending three-year information-sharing agreement, the Census Bureau would use the DHS data to better determine who is a citizen and eligible to vote by “linking citizenship information from administrative records to census microdata”.

“All uses of the data are solely for statistical purposes, which by definition means that uses will not directly affect benefits or enforcement actions for any individual,” according to the 13-page document signed by the bureau.

Amy O’Hara, who until 2017 directed Census Bureau efforts to expand data-sharing with other agencies, said she was surprised that a plan was in the works for sharing alien numbers with the bureau.

“I wish that we were not on this path,” she said. “If the citizenship question hadn’t been added to the census, this agreement never would have been sought.”

In previous administrations, government lawyers advised census researchers to use a minimal amount of identifying data to get their jobs done, said O’Hara, now the co-director of Georgetown University’s census research center. During her tenure, the bureau never obtained anything as sensitive as alien numbers, which O’Hara called “more radioactive than fingerprints”. The numbers are assigned to immigrants seeking citizenship or involved in law enforcement action.

Some privacy groups worry the pending agreement is an end-run around the courts.

“What’s going on here is they are trying to circumvent the need for a citizenship question by using data collected by another agency for a different purpose,” Jeramie Scott, an attorney at the Electronic Privacy Information Center. “It’s a violation of people’s privacy.”

The quiet manner in which the agencies pursued sharing records could stoke concerns that the Trump administration may be seeking to create a registry of noncitizens, said Kenneth Prewitt, who was census director from 1998-2001 and is now a Columbia professor.

Census scholars say that could not happen without new legislation, which is not likely under the Democratic majority in the House of Representatives.

In mid-April, the supreme court will hear arguments as to whether the 2020 census can include a citizenship question, with a decision expected weeks later.

Next week, the commerce secretary, Wilbur Ross, whose department oversees the census, is set to testify before the Senate on his role in the controversy.

The Census figures hugely in how political power and money are distributed in the US, and underreporting by noncitizens would have an outsized impact in states with larger immigrant populations. Political clout and federal dollars are both at stake because 10-year survey results are used to distribute electoral college votes and congressional district seats, and allocate more than $880bn a year for services including roads, schools and Medicare.

A March 2018 memo to Ross from the Census Bureau’s chief scientist says the DHS data on noncitizens could be used to help create a “comprehensive statistical reference list of current US citizens”. The memo discusses how to create “baseline citizenship statistics” by drawing on administrative records from DHS, the Social Security Administration, state department and the Internal Revenue Service, in addition to including the citizenship question in the census.