The Texan billionaire who married Anna Nicole Smith in the last year of his life never intended to leave her any part of his fortune, a federal appeals court has ruled.

The ninth US circuit court of appeals backed a Houston jury that said J Howard Marshall was mentally fit and under no undue pressure when he wrote a will leaving nearly all his $1.6bn (£1bn) estate to his son, E Pierce Marshall, and nothing to Smith.

Friday's ruling was the latest development in a 15-year battle. Smith, who died in 2008, claimed Marshall had promised her more than $300m

The battle between Smith and Marshall started in a Houston probate court and continued to the US supreme court, outliving the two combatants. It may reach the high court again.

Kent Richland, a lawyer for Smith's estate vowed to appeal against the latest ruling, possibly to the supreme court, on different issues than those it first considered.