Exxon Corp. on Thursday appealed the $5.3 billion verdict awarded to fishermen, natives and others harmed by the 11-million gallon Exxon Valdez oil spill.

In a brief filed with the 9th U.S. Circuit Court of Appeals, the oil company argued that punitive damages weren’t warranted because Congress had already spelled out the actions that were needed to punish oil spillers and deter oil spills.

And even if punitive damages are allowed, a $900 million settlement with the state reached in 1991 precludes any more punitive damages, Exxon said in a news release.

A federal jury awarded $5 billion in punitive damages in 1994 for the 1989 spill in Prince William Sound.

The company said the $3.5 billion it has already spent to clean up the spill is punishment enough.

“The punitive damage verdict sends a perverse message that those who acknowledge their responsibilities and take prompt and costly remedial action will still face disproportionate punishment,” Exxon chairman Lee R. Raymond said.