California's voter-approved Proposition 50 plan for new congressional districts mandates "racial gerrymandering" in favor of Hispanic voters in violation of the equal protection clause, the U.S. Department of Justice alleges in a federal lawsuit filed Thursday against Gov. Gavin Newsom.

The 18-page complaint concerns Proposition 50, which Newsom championed to passage on election day as a way of flipping five U.S. House seats for Democrats in next year's elections.

"The end result is a map that manipulates district lines in the name of bolstering the voting power of Hispanic Californians because of their race," states the federal government's suit. "Our Constitution does not tolerate this racial gerrymander."

The suit seeks a court order declaring Proposition 50 unlawful and stopping California from using the new congressional district maps in the 2026 midterms and beyond.

The state legislature's redistricting proposal followed a move by Texas Republicans to redraw their own maps, at President Donald Trump's urging, to pick up five seats in next year's elections. Texas Gov. Greg Abbott officially signed the state's new congressional map into law in August.

Although the U.S. Supreme Court has allowed race-conscious redistricting to rectify violations of the Voting Rights Act, no one contends that California's preexisting map discriminated on the basis of race, the federal government says.

The "Proposition 50 map does," it asserts.

The complaint notes that legal concerns over district lines drawn to advantage one political party over another is "beyond the reach of the federal courts," citing the Supreme Court's 2018 decision in Rucho v. Common Cause.

Racial gerrymanders, however, are unconstitutional, the suit underscores.

States "generally may not use race as a 'predominant criterion' in achieving partisan goals," it says, citing the high court's 2017 decision in Cooper v Harris.

The federal government points out that a press release issued by state Sen. and Senate President pro tempore Mike McGuire in August says that the Proposition 50 map "retains and expands" districts "that empower Latino voters."

The suit brings causes of action for racial gerrymandering in violation of the equal protection clause of the 14th Amendment and intentional racial discrimination in violation of the Voting Rights Act.

"The U.S. Department of Justice is moving swiftly to prevent these illegal maps from tainting our upcoming elections. California is free to draw congressional maps, but they may not be drawn based on race," said First Assistant U.S. Attorney Bill Essayli of the Central District of California in an announcement about the lawsuit.

The lawsuit seek to join litigation filed last week by Assemblymember David J. Tangipa, R-Fresno, and other Golden State Republicans.

In a motion to intervene filed Thursday, the Justice Department said counsel for Tangipa and the other plaintiffs do not oppose the request, and counsel for Newsom and co-defendant California Secretary of State Shirley Weber told the federal government on Wednesday they "take no position" on the motion.

On Wednesday, the California federal judge overseeing that case granted the Democratic Congressional Campaign Committee's motion to intervene.

The lawsuit is the one of several redistricting legal battles playing out across the nation as Republicans and Democrats fight for control of Congress.

As lawmakers face off in court, the Supreme Court kicked off its October 2025 term last month by revisiting the legality of Louisiana's congressional map, which has two majority-Black voting districts. Depending on how the justices decide, the dispute could spell the end for the Voting Rights Act.

In response to the Justice Department's lawsuit, Newsom's office released a single-sentence statement Thursday: "These losers lost at the ballot box, and soon they will also lose in court."

In a social media post on Thursday, Attorney General Pamela Bondi announced the lawsuit, saying, "Newsom should be concerned about keeping Californians safe and shutting down antifa violence, not rigging his state for political gain."

The Justice Department did not respond to a request for comment Thursday.

The federal government is represented by Jesus A. Osete, Matthew Zandi, Maureen Riordan, Andrew Braniff, David Goldman, Joshua R. Zuckerman and Greta Gieseke of the DOJ's Civil Rights Division, and Bilal A. Essayli and Julie A. Hamill of the U.S. Attorney's Office for the Central District of California.

Counsel information for the defendants was not available Thursday.

The case is Tangipa et al. v. Newsom et al., case number 2:25-cv-10616, in the U.S. District Court for the Central District of California.

--Editing by Adam LoBelia.