All 27 charges of conspiracy, theft and money laundering against Papua New Guinea lawyer Paul Paraka have been dropped.
The Post Courier reported a magistrate had ruled the charges laid against Mr Paraka by Taskforce Sweep were an abuse of the court process.
The case has spanned more than five years and relates to payments made to Mr Paraka's law firm for legal services rendered to the PNG government between 2007 and 2013.
The magistrate said the 27 charges - 17 counts of conspiracy to defraud, five counts of theft under false pretences and five counts of money laundering - were laid by Taskforce Sweep one month after it had been abolished.
That meant the taskforce had no jurisdiction to lay the charges at the material time, making its actions an abuse of the formal court process, the magistrate said.
The taskforce, a police anti-corruption unit, was mandated by the Peter O'Neill led government in late 2011.
But it was ordered to disband in June 2014 by the cabinet after it served an arrest warrant on Mr O'Neill for payments to the law firm.