The Navajo Nation on Thursday filed another federal breach of contract case against the U.S. Department of the Interior over funding for its judicial branch, the latest lawsuit in an ongoing battle against the agency over tens of millions of dollars the tribe says it has been shortchanged.

In its filing with the D.C. federal court, the tribe says it requested $17,055,477 for the Navajo Nation Judicial Branch for calendar year 2023 but the DOI has proposed to pay only $1,749,531.

The claim is similar to one the tribe filed in April saying the DOI approved only $1.5 million of a $17 million request for 2022. In June, U.S. District Judge Tanya S. Chutkan issued an order staying that case while the Navajo Nation appeals her March 2022 decision in related, consolidated proceedings over previous years of judicial funding.

The suit filed Thursday also accuses the government of violating the Indian Self-Determination and Education Assistance Act and related regulations, as well as a contract made under the federal law.

Under the ISDEAA and governing regulations, the U.S. government is not allowed to reject an Indian tribe's proposed funding if it is substantially the same as the amount requested in its prior contract, the suit claims.

The $17 million the Navajo Nation requested from the DOI for its judicial branch is the same amount sought each year from 2016 through 2022, according to the complaint.

"Defendants' partial declination of the Nation's proposed funding of $17,055,477 for CY 2023 violated their obligations under the ISDEAA and its implementing regulations and constitutes a material breach of contract," the Navajo Nation's suit states.

The Nation and the Department of the Interior agreed to a "self-determination contract" covering operations of the Nation's Judicial Branch for a five-year term from 2012 through 2016, and then entered into renewal contract for another five years starting in 2017, according to the complaint. Another five-year renewal was inked to start in 2022.

In its latest complaint, the Navajo Nation notes that in 2014, it first sought $17 million in funding — an amount it deemed approved by law because the Bureau of Indian Affairs missed a deadline to respond. By November of that year, the tribe filed suit over the agency's refusal to fulfill its funding request. The federal government pushed back, saying the request represented more than an 800% increase over prior years.

In June 2020, Judge Chutkan granted the Navajo Nation's bid to fund the tribe's court in light of the D.C. Circuit's conclusion that the proposed 2014 funding agreement was deemed approved when the government missed a deadline to respond.

That case also led to a partial win for the Navajo Nation in the consolidated litigation, as Judge Chutkan awarded the tribe more than $31 million, while also dismissing a slew of the tribe's suits.

The Navajo Nation sued the federal government over every successive funding agreement from 2015 to 2020, claiming it had not abided by the $17 million funding floor.

In her March 2022 decision, the judge awarded the Navajo Nation two separate awards of about $15 million for the calendar years of 2015 and 2016, saying they were part of the first five-year agreement contract penned in 2012. However, the judge ruled that the annual funding agreements for the second five-year contract from 2017 to 2021 were not "successor funding agreements to the 2014" funding floor. The Navajo Nation has appealed that ruling, which is pending before the D.C. Circuit.

The first suit of the six was filed in 2016, with the Navajo claiming the DOI only paid about $1.3 million out of a $19 million funding request for 2015. Subsequent suits followed for each calendar year, all claiming the DOI failed to provide the adequate funding.

Philip Baker-Shenk, an attorney representing the Navajo, declined to remark Thursday on the latest lawsuit. The DOI did not immediately respond to a request for comment.

The Navajo Nation is represented by Steven D. Gordon and Philip Baker-Shenk of Holland & Knight LLP.

Counsel information for the U.S. Department of the Interior was not available on Thursday.

The case is Navajo Nation v United States Department of the Interior, case number 23-cv-00035, in the United States District Court for the District of Columbia. The lead case number is Navajo Nation v United States Department of the Interior, case number 1:16-cv-00011, in the United States District Court for the District of Columbia.

--Additional reporting by Joyce Hanson, Adrian Cruz, Humberto J. Rocha and Emma Whitford. Editing by Michael Watanabe.