The 5-3 majority said that in the maritime law context, there should be a 1:1 ratio between compensatory and punitive damages. A trial judge had awarded $507.5 million in compensatory damages to a class of fishermen who suffered losses from the 1989 oil spill, so Justice David Souter, who wrote the majority opinion, said the punitive award should match that figure. The award had already been reduced to $2.5 billion on appeal, so the decision saved Exxon Mobil nearly $2 billion.

Even though the ruling was based on maritime law, a unique branch of federal common law, the Souter opinion was full of concern about unpredictable “outlier” verdicts against corporations.