A federal appeals court on Friday cut in half a $5 billion jury award for punitive damages against Exxon Mobil Corp. in the 1989 Valdez oil spill that smeared black goo across roughly 1,500 miles of Alaskan coastline.

The case, one of the nation’s longest-running, non-criminal legal disputes, stems from a 1994 decision by an Anchorage jury to award the punitive damages to 34,000 fishermen and other Alaskans. Their property and livelihoods were harmed when the Valdez oil tanker struck a charted reef and spilled 11 million gallons of crude oil.