CHICAGO – The Illinois legislature’s decision to direct elections officials to use legislative redistricting plans that rely on population estimates rather than decennial Census data is unconstitutional, according to a federal-court lawsuit filed late Thursday.

MALDEF (Mexican American Legal Defense and Educational Fund) filed the lawsuit on behalf of a group of registered voters. The suit challenges the plan, adopted by the Illinois General Assembly and signed on June 4 by Gov. J.B. Pritzker, as a violation of the U.S. Constitution’s Fourteenth Amendment Equal Protection guarantee of “one person, one vote.”

“Illinois voters, including the growing Latino voter community, are entitled to districts that accurately reflect the population as determined by the constitutionally mandated decennial census,” said Thomas A. Saenz, MALDEF president and general counsel.  “Ultimately, the General Assembly will have to redraw lines for the 2022 elections using the proper decennial census data.”

At issue, is the state’s attempt to rely on the American Community Survey’s (ACS) population estimates rather than use the U.S. Census Bureau’s redistricting data that is based on population counts from the 2020 Census.

The ACS is a population survey conducted over five years and samples only about 2.5 percent of the U.S. population. The survey does not have the most current population data nor does it provide the necessary geographic detail known as census block data that is required to draw equal electoral districts.

By contrast, the decennial census counts every person as required by the Constitution and is, therefore, a more accurate set of data for creating the equal districts needed to ensure “one person, one vote.”

“ACS data is not adequate to ensure the constitutional guarantee of one-person-one-vote,” said MALDEF attorney Francisco Fernandez-del Castillo. “Using the ACS estimates to draw district boundaries puts all Illinois voters — especially those in in traditionally underrepresented communities, such as Latinos — at risk of being disenfranchised.”

The lawsuit asks for a three-judge district court to toss out the plans.

Because of COVID-19, the Census Bureau’s release of useable census data for purposes of redistricting has been delayed until September. Since Illinois lawmakers have only until June 30 to approve maps, the state’s General Assembly moved forward using the ACS population estimates and other unspecified “election data.”

The complaint was filed in the U.S. District Court for the Northern District of Illinois Eastern Division. Defendants include the Illinois State Board of Elections and its members, Don Harmon, President of the Illinois Senate, and Emanuel “Chris” Welch, Speaker of the Illinois House of Representatives.

Read the lawsuit HERE.