In the case, a legal aid group had taken the inventive step of assuming the role of a whistle-blower revealing abuses in the handling of a popular type of government-backed mortgage.
But Judge Jack Zouhary of Federal District Court for the Northern District of Ohio ruled on Tuesday that the group, Advocates for Basic Legal Equality, did not act as a whistle-blower in the way envisioned by the False Claims Act, the legislation that was the basis for the group's action.
The lawsuit was filed against U.S. Bank, a unit of U.S. Bancorp, one of the nation's largest financial firms. A spokesman for the bank declined to comment on Judge Zouhary's decision.
George Thomas, a staff lawyer at Advocates for Basic Legal Equality, said that the group was weighing whether to appeal. "We feel strongly that ABLE is appropriate as a whistle-blower," he said.
The case focuses on mortgages guaranteed by the Federal Housing Administration, which is part of the Department of Housing and Urban Development. When a borrower defaults on such mortgages, the government makes payments to the bank that made the loan to make it whole. The F.H.A.'s rules require banks to work with defaulting borrowers to find ways to become current on their loans.
But the legal aid group claimed that U.S. Bank did not follow those rules in many cases. By not fulfilling the requirement to work with borrowers on defaulted mortgages, and by collecting money for such loans from the F.H.A., U.S. Bank made "false claims" against the government, the group contended.
But Judge Zouhary, in a 19-page ruling, said there was a big flaw in Advocates for Basic Legal Equality's case.
Private citizens and groups can bring actions under the False Claims Act, and they can win financial awards if the actions are successful. The act also says that such whistle-blowers must provide information that is original or unique.
Judge Zouhary ruled that the group had relied on public information: "ABLE does not become an original source of information by putting its own spin on prior public disclosures of U.S. Bank's regulatory failures," he wrote.
The group had argued in its complaint that it had provided new material that was not public. It said it had interviewed people who had defaulted on U.S. Bank mortgages and said that the bank had not contacted those borrowers to talk about ways to become current again.
"We did present information that was unique and that no one was previously aware of," Mr. Thomas said.
Judge Zouhary did give a measure of support to the legal aid group's complaint, however. His ruling, for instance, disagreed with some of U.S. Bank's arguments that its actions did not result in false claims.
"U.S. Bank is also incorrect in asserting that compliance with HUD's loss mitigation regulations is not material to HUD's decision to pay an insurance claim," the judge wrote, referring to the Department of Housing and Urban Development. (In the mortgage industry, loss mitigation can include efforts to get borrowers in default on a payment plan they are more likely to be able to afford.)
The lawsuit by Advocates for Basic Legal Equality suffered an early blow when the Justice Department declined to join the action. But the agency later submitted "statements of interest" to the Federal District Court in Ohio that supported some of the group's arguments and disagreed with some of those advanced by U.S. Bank.
By PETER EAVISMAY 13, 2015
A version of this article appears in print on May 14, 2015, on page B6 of the New York edition with the headline: Judge Denies Whistle-Blower Status in U.S. Bank Case . Order Reprints|Today's Paper|Subscribe