The California Supreme Court yesterday declined to hear an appeal of a $US290 million personal injury against Ford stemming from the death of three people in 1993 when their Bronco sport utility rolled over, Reuters reported.

The court, in a four-to-three decision, decided not to hear the case, Ford spokeswoman Kathleen Vokes told Reuters.

"This is an extreme and unconstitutional punitive damage award and we will ask the US Supreme Court to overturn it," she added, according to Reuters.

Reuters said that the plaintiffs in the case had argued that the Bronco was prone to roll over and had a weak, poorly designed roof that Ford knew could fail.

Ford officials had denied the rollover allegations and said the removable, fibreglass roof panel on the Bronco exceeded federal safety standards at the time the vehicle was made, Reuters said.