KEY POINTS:
Federal Government moves to extradite American stock market guru Larry Williams - the father of Hollywood actress Michelle Williams - have been ruled invalid by the Federal Court.
Williams is wanted by the United States Internal Revenue Service on charges of wilfully attempting to evade US$1.5 million ($2.14 million) in taxes from 1999 to 2001.
He is grandfather to Matilda - Michelle Williams' daughter with Australian film star Heath Ledger.
The 64-year-old was arrested on an extradition warrant in May last year, when he arrived in Sydney ahead of a month-long speaking tour of Australia and New Zealand.
Williams last year challenged the validity of a notice issued by then federal Justice Minister Chris Ellison authorising a magistrate to rule on the US extradition request.
He argued that Ellison acted on advice from the US which did not identify precisely enough why his extradition was sought.
- AAP