BISMARCK, N.D. (AP) — North Dakota’s 2021 legislative redistricting plan violates the rights of two Native American tribes because it dilutes their voting strength, a federal judge ruled Friday.

U.S. District Chief Judge Peter Welte said the redrawn legislative districts violated the Voting Rights Act of 1965. The ruling came months after a trial held in June in Fargo.

In his ruling, Welte said the plan approved by the state Legislature to redraw voting districts in accordance with the latest census data “prevents Native American voters from having an equal opportunity to elect candidates of their choice” - a violation of the landmark civil rights law.

Welte gave the Republican-controlled Legislature until Dec. 22 “to adopt a plan to remedy the violation.”

The Turtle Mountain Band of Chippewa Indians and the Spirit Lake Tribe alleged the 2021 redistricting map “packs” Turtle Mountain tribal members into one House district and leaves Spirit Lake out of a majority-Native district.

The tribes sought a joint district and unsuccessfully proposed to the Legislature a single legislative district encompassing the two reservations, which are roughly 60 miles (97 kilometers) apart.

North Dakota Republican Secretary of State Michael Howe, who is named in the lawsuit, did not immediately comment on the ruling. He said he was still processing documents sent to his office and planned to meet with attorneys on Friday afternoon.

Lawmakers involved in redistricting cited 2020 census data meeting population requirements of the Voting Rights Act for creating the two subdistricts.

North Dakota has 47 legislative districts, each with one senator and two representatives. Republicans control the House of Representatives 82-12, and the Senate 43-4. At least two lawmakers, both House Democrats, are members of tribes sharing geography with North Dakota.

A three-judge panel earlier this month dismissed another federal lawsuit that targeted the redistricting, brought by two local Republican Party officials who challenged new House subdistricts comprising tribal nations as unconstitutional “racial gerrymandering.”

The Legislature created four subdistricts in the state House of Representatives, including one each for the Fort Berthold and Turtle Mountain Indian reservations.