An appeals court says it cannot reduce a $20 million restitution order against the public relations consultant who partnered with lobbyist Jack Abramoff to bilk Indian tribes out of millions in inflated fees.

Michael Scanlon is serving a 20-month sentence after pleading guilty in part to defrauding the tribes of their right to "honest services." Abramoff persuaded tribes that hired him for lobbying to pay inflated fees for Scanlon's public relations services, and the two secretly split the profits.

The Supreme Court weakened the honest services law last year and Scanlon argued the $20 million he's been ordered to repay his victims should be lowered to reflect that ruling.

But a three-judge panel of the U.S. Court of Appeals in Washington ruled Friday that courts cannot modify plea agreements.