BISMARCK, N.D. (AP) — North Dakota will sue the federal government to try to recoup the $38 million it spent policing the prolonged protests against the Dakota Access oil pipeline — a tactic one expert believes has little chance of success.

The Army Corps of Engineers didn’t respond to an administrative claim filed last July, so a lawsuit is the next step, Attorney General Wayne Stenehjem said Tuesday. He didn’t have an estimate on the cost, which will be funded either through his department’s existing budget or through a state fund set up for such litigation.

Justice Department spokesman Wyn Hornbuckle declined comment.

Thousands of opponents of the $3.8 billion pipeline that’s been moving North Dakota oil to Illinois since June 2017 gathered in southern North Dakota in 2016 and early 2017, camping on federal land and often clashing with police, resulting in 761 arrests over six months.

North Dakota contends the Corps allowed protesters to illegally camp without a federal permit. The Corps has said protesters weren’t evicted due to free speech reasons.

University of St. Thomas law professor Gregory Sisk, an expert on civil litigation with the federal government, considers North Dakota’s case “a long shot.” He said lawsuits that essentially allege the government failed at its job typically don’t succeed, and he gives North Dakota “a 1 in 10 chance.”

Stenehjem said he thinks the state has “a solid claim.” He said he heard similar skepticism when the state sued Minnesota several years ago over a law that impacted North Dakota electricity exports, and “we won.”

President Donald Trump last year denied a state-requested disaster declaration to cover the state’s costs. The Justice Department eventually did give the state a $10 million grantfor policing-related bills. Texas-based pipeline developer Energy Transfer Partners chipped in $15 million .

Stenehjem maintains the $25 million doesn’t impact the federal government’s responsibility for the $38 million total cost. He said it’s up to the Corps to prove that it deserves an offset for the Justice Department grant, and that “the federal government is not entitled to take advantage of a donation from a private party.”

Stenehjem said the state would be open to settlement talks, but Sisk questions if the Corps will be willing to negotiate because it could set a bad precedent for the agency.

Any money the state gets for protest policing costs, donated or otherwise, goes toward compensating agencies that paid out money and repaying money borrowed from the state-owned Bank of North Dakota, with any extra going into the state’s general fund, according to Stenehjem.