A group of voters from several states filed a lawsuit in US federal court Friday to halt enforcement of a presidential memorandum that would alter the census count by leaving out undocumented immigrants.

The US Constitution mandates that a census be carried out every ten years, while section 2 of the Fourteenth Amendment requires “counting the whole number of persons in each state, excluding Indians not taxed.” Courts, including the Supreme Court, have traditionally interpreted the word “persons” to include non-citizens regardless of their immigration status. The July 21 memorandum would make it government policy “to exclude from the apportionment base aliens who are not in a lawful immigration status.”

The number of a state’s representatives in the House of Representatives depends on the population of the state, and not counting undocumented immigrants will radically alter state population totals and therefore the number of representatives each state has in the House. Voters from California, Nevada, New York, Florida, and Texas, with the support of the National Redistricting Foundation, filed suit in the District Court of Maryland, alleging that the president’s memorandum is part of an “ongoing discriminatory scheme to dilute the voting power of non-whites, Hispanics, and immigrants of color, and to shift political power to non-Hispanic whites.” They claim they will be harmed by the exclusion of undocumented citizens from the census, because the resulting reapportionment of representatives will cause them to lose political representation and lead to an “under-allocation of federal funding to Plaintiffs’ communities.”

Plaintiffs are asking the court to find the president’s memorandum unconstitutional, and they seek to permanently enjoin the president and his administration from taking any action that would limit or exclude the counting of undocumented immigrants in the census.