The Census Bureau plans to ask people if they are U.S. citizens in the 2020 count of the nation’s population, igniting fears that the information could be used to target those in the country illegally.

Census officials said the question is being reinstated for the first time since 1950 to help enforce the Voting Rights Act and that there are safeguards in place to prevent any abuse of the information. It is illegal to release information that would identify individuals or families.

But that does not mean that census data has not been used to target specific populations in the past.

In fact, information from the 1940 Census was secretly used in one of the worst violations of constitutional rights in U.S. history: the internment of Japanese Americans during World War II.

In papers presented in 2000 and 2007, historian Margo J. Anderson of the University of Wisconsin at Milwaukee and statistician William Seltzer of Fordham University found evidence that census officials cooperated with the government, providing data to target Japanese Americans.