Trump administration officials have privately discussed the possibility that in the future census information could be shared with law enforcement, according to documents filed in a legal challenge over plans for a new citizenship question on the 2020 survey.

The subject came up after a Democratic lawmaker asked whether responses to the survey could ever be shared with law enforcement agencies, something that has been strictly illegal according to federal law governing the census.

After a congressional hearing in May about the citizenship question, Rep. Jimmy Gomez (D-Calif.) submitted a written query about whether the Justice Department agreed with a memo it had issued in 2010 saying the USA Patriot Act could not override the confidentiality of the census.

In a June 12 email, department officials discussed among themselves how to answer Gomez’s question in a way that left the answer open. Justice Department attorney Ben Aguinaga suggested to acting assistant attorney general John Gore that they not say “too much” in response to Gomez’s question, in case the issue were to “come up later for renewed debate.”

Confidentiality is considered a fundamental premise of the census and crucial to the success of the constitutionally mandated count, which surveys each household in the country every 10 years. That confidentiality is enshrined in the Census Act of 1879.

In 1954, Congress codified the rules, which say that the Commerce Department, which oversees the survey, cannot share the data with any other government agency or court. Violators are subject to up to five years in federal prison and up to $250,000 in fines. The law can be changed only by Congress.

The Justice Department email was included in documents filed in San Francisco federal court for a trial slated to begin in January.

It appeared to leave open the possibility of reconsidering the 2010 memo, which was issued at the time of the first decennial census to be conducted after the 9/11 attacks and the creation of the USA Patriot Act.

The Justice Department declined to comment on the email or whether census confidentiality is subject to debate. Acting Census Bureau director Ron S. Jarmin has blogged about the importance of the count’s confidentiality.

The revelation comes at a time when immigrant communities feel besieged and are already worried about participating in the census, which determines the allocation of $800 billion a year in federal funds along with congressional apportionment.

Gomez’s question asked if there was “any provision of any law that might compel Census to disclose confidential census data for law enforcement or national security purposes?”

In the email to Gore about how to respond, Aguinaga wrote: “I don’t think we want to say too much there in case the issues . . . or related issues come up later for renewed debate. So, I’ve just said that the Department will abide by all laws requiring confidentiality.” It is unclear whether Gore answered the email. Gomez’s office said it received a reply with that wording months later.

Six lawsuits have challenged the administration’s decision to add a citizenship question to the count, saying it will dissuade immigrants and their families from filling out the forms and lead to an inaccurate and more costly count.

Filling out the census is required by law. The cost of the count increases when census workers must circle back to households that do not respond to the forms in the initial round.

Additional uncertainty about whether their responses will be protected probably would further undermine the count, census experts say.

“It could reinforce fears about how this administration could use census responses,” said Terri Ann Lowenthal, a former staff director of the House census oversight subcommittee. Gomez’s question “should have been an easy opportunity for the Justice Department to reaffirm that there is an ironclad wall around personal census responses.”

“If the administration and the commerce secretary don’t right that ship quickly, the entire census could be in trouble,” she added.

Although raising doubts about confidentiality could have a chilling effect on response rates, Thomas Wolf, counsel with the Democracy Program at the Brennan Center for Justice, which has filed briefs in the current lawsuits, said the Justice Department does not have the authority to change the rules.

“The Census Act makes it absolutely clear that individual census responses cannot leave the Commerce Department” and that general census data cannot be shared for law enforcement purposes, Wolf said. “The Department of Justice has absolutely no say in whether the census data can be shared; [it] has to follow federal statutes just like everyone else.”

He added that “the only way these statutes can change is if Congress changes them, and I’m highly skeptical that a Democrat-led House is going to change them.”

Instead, Wolf said, the discussion may have been an example of government officials floating an idea to see if it is workable. “This administration likes to test the fences,” he said. “This fence is an electrical fence; it would be in­cred­ibly illegal.”

House Democrats have vowed to push hard against threats to the count. Gomez, who sits on the House Oversight and Government Reform Committee, said Monday that “the new Democratic House majority will do everything in our power to directly address these anti-immigrant efforts” related to the 2020 count. “These emails prove that the Trump administration is using every tool at their disposal to vilify our immigrant communities, including the 2020 Census.”