Democrats on the House Oversight and Government Reform Committee are demanding that the Justice Department hand over documents detailing the Census Bureau’s decision to include a question about citizenship on the 2020 census.

The Justice Department sent the Commerce Department a letter in December asking for a citizenship question to be included on the upcoming Census questionnaire. In March, the Commerce Department, which houses the Census Bureau, announced the question would appear and cited the need to ensure better enforcement of the Voting Rights Act.