A U.S. Appeals Court on Friday ordered $5 billion US in damages awarded against Exxon Mobil Corp. for the 1989 Valdez oil spill to be cut by half.

The case is one of the longest-running in U.S. legal history. Friday's decision marked the third time that the Appeals Court has ordered a reduction to the massive award.

The Exxon Baton Rouge, top, off-loads crude oil from the Exxon Valdez after it ran aground in Prince William Sound in Alaska in this March 26, 1989 photo. The Exxon Baton Rouge, top, off-loads crude oil from the Exxon Valdez after it ran aground in Prince William Sound in Alaska in this March 26, 1989 photo.
(Stapleton/Associated Press)

In 1994, a jury in Anchorage, Alaska, awarded the damages to 34,000 Alaskans, including fishermen, who were hurt when the Exxon Valdez oil tank ran aground and spilled over 41 million litres of crude oil.

In a 2-1 decision, the Appeals Court ordered that a specific amount in damages be set for the award.

"It is time for this protracted litigation to end," the court said.