The judge ruled that the son had tried to rob Smith of her rightful inheritance by mounting a campaign of deceit and dishonesty.
But on Thursday a three-judge panel of the US 9th Circuit Court of Appeals, based in San Francisco, reversed that decision, saying she was not mentioned in his trust and will, although she was given about $6 million in gifts in 1994.
"Although J. Howard Marshall II was married to Vickie Lynn Marshall, no provision for distributions of income or principal of the trust estate was made in favour of the settlor's spouse," Judge Robert Beezer wrote.