A federal judge is allowing voters from Arizona and elsewhere to be parties to a lawsuit filed in Alabama. The lawsuit centers on counting undocumented immigrants in the upcoming 2020 Census.

Congressman Mo Brooks, a Republican from Alabama, sued the federal government in May to prevent it from counting undocumented immigrants. Brooks argues that by including those residents, Alabama’s federal funding and representation in Congress would decline because the state has a lower influx of unauthorized immigrants than others.

The initial complaint contends the census is "robbing the people of the State of Alabama of their rightful share of political representation."

Thomas Saenz, president and general counsel of the Mexican American Legal Defense and Educational Fund (MALDEF), called the Alabama suit “frivolous,” because the census has always followed the language in the Constitution.

“The Constitution is quite clear that you count all residents. And that would be true regardless of whether it hurt one state or another,” he said.

The text of Article I, Section 2 of the U.S. Constitution says Congressional representation is to be “determined by adding to the whole Number of free Persons.”

But Saenz doesn’t want to leave the defense in the case up to the Trump administration, which is why MALDEF is joining in. On Thursday, the judge allowed his clients, including the Arizona-based group Chicanos Por La Causa, to intervene as defendants in the suit.

The case is separate from the seven lawsuits against putting a citizenship question on the census.