Washington ? A federal appeals court ruled Friday that the Interior Department must account for century-old land royalties owed to American Indians, reversing a lower court’s ruling that the task is impossible.

A 2008 decision by U.S. District Judge James Robertson said Interior had unreasonably delayed an accounting but added that the complicated task was ultimately impossible. He later ruled the Indian plaintiffs are entitled to $455 million, a fraction of the $47 billion or more they have said they are owed.

The appeals court said Friday that that court erred in freeing the government from the accounting burden. Chief Judge David B. Sentelle of the U.S. Court of Appeals for the D.C. Circuit said the decision essentially allowed the Interior Department “to throw up its hands and stop the accounting.”

“Without an accounting, it is impossible to know who is owed what,” Sentelle wrote. “The best any trust beneficiary could hope for would be a government check in an arbitrary amount.”

The long-running suit, first filed 13 years ago, claims the Indians were swindled out of royalties overseen by the Interior Department since 1887 for things like oil, gas, grazing and timber.

The three-judge panel acknowledged that the task is a complicated one and said the Interior Department should focus on the “low-hanging fruit” and not muddy the process by spending time and money to account for closed accounts or those in probate, for example.

“We must not allow the theoretically perfect to render impossible the achievable good,” Sentelle wrote.

Indian plaintiffs, led by Elouise Cobell, a member of the Blackfeet Tribe from Montana, have argued that the government has for a long time improperly accounted for the money and should pay it back with some form of interest.

Cobell expressed disappointment in the ruling Friday, saying the decision will just delay the trial even further. “For hundreds of thousands of Indians, including children, the elderly, and the infirm who depend upon their trust funds for food, clothing, shelter, and health care, this ruling means that many more years will pass before they can hope to secure trust funds that the government has withheld unconscionably and in breach of trust duties that it has owed for generations. “

The Department of Interior would not comment on the specifics of the ruling.

In 1994, Congress demanded that the department fulfill an obligation to account for money received and distributed. Two years later, when account statements still had not been reconciled, Cobell joined with others in suing.

Because many of the records have been lost, it has since been up to the courts to decide how to best estimate how much individuals should be paid, or how the money should be accounted for. Many of them are nearing the end of their lives.

The class-action suit deals with individual Indians’ lands and covers about 500,000 Indians and their heirs. Several tribes have sued separately, claiming mismanagement of their lands.