A US federal judge has dismissed all charges against a Cork businessman accused of involvement in a corporate accounting scandal which wiped more than $1 billion (€759.5 million) from the share price of communications giant Enterasys.

Federal district court judge Paul Barbadoro ruled that the US Department of Justice had violated Jerry Shanahan's right to a speedy retrial on fraud charges.

Mr Shanahan, from Carrigaline, Co Cork, was due to be retried next month on fraud charges after a jury was unable to reach a decision last December.

He is the only former Enterasys executive put on trial last year who was not convicted on fraud charges.

Judge Barbadoro noted that the two main prosecutors in the case had been delayed with other cases.

The lead prosecutor had been caught up in a complex insider trading case in Denver, Colorado.

Her co-counsel was involved in a tax evasion case which dragged on after the convicted defendants barricaded themselves into a home and threatened to kill themselves and others if they were arrested.

Judge Barbadoro ruled that prosecutors had not retried Mr Shanahan within 70 non-excluded days, as is required by federal law.

"Shanahan was not responsible for the court's failure to retry him within 70 days," the judge said. "I see no evidence, however, of bad faith, gamesmanship or intentional delay in the government's actions."

The judge accepted that both prosecutors had faced extremely busy trial schedules and had "begun working full-time on complex trials almost immediately following Shanahan's original trial".

However, he rejected Mr Shanahan's claim that he had suffered an undue physical and psychological hardship while waiting for the retrial.

"The effects he describes are no different from those that are experienced by every defendant who must await the disposition of serious criminal charges.

"Shanahan is not in custody, and I allowed him to return to Ireland to be with his family while he awaited retrial," the judge added.

Mr Shanahan stated in court documents that it was difficult to put into words the "emotional and psychological stress" as well as "emotional and physical turmoil" which he and his family had endured during his initial trial and while waiting for the retrial to proceed.

Mr Shanahan (42), the former chief operations officer with Enterasys, was accused of setting up fake deals with customers to boost the company's share price after the company spun off from a parent company, Cabletron, in 2001.

He has a degree in electrical engineering from University College Cork and a master's degree in business from the University of Limerick.