A Boston court is set to rule early next week on whether David Drumm can be released on bail pending his extradition hearing.
Lawyers for the former Anglo Irish Bank CEO argued today that a lower court had made "a series of legal and factual errors" in denying bail to Mr Drumm.
The US Attorney Amy Burkart dismissed claims about his treatment in detention, saying that "while he used to be a CEO, he was now a federal detainee".
Mr Drumm has spent almost three months in a federal prison since his arrest in early October, pending an extradition hearing to return him to Ireland to face 33 charges.
He was refused bail last month after a Boston court found that he had failed to provide evidence that special circumstances related to him that merited his release on bail.
Today dozens of Mr Drumm's immediate family members and supporters were in court, as the former banker made another attempt to be released on bail pending his extradition hearing.
His lawyer Edward McNally said it was "abundantly clear" that the original judge had made a series of "unreasonable errors" in denying bail.
He argued that there was no diplomatic necessity to keep Mr Drumm in custody…saying that the delay in bringing charges against him showed that "Ireland itself had not placed a high premium on the case or the return of Mr Drumm".
The US Attorney countered that the Irish authorities had not delayed unnecessarily, and in fact by refusing to co-operate with them, Mr Drumm had contributed to the long time-frame.
Drumm's lawyers also said circumstances of Mr Drumm's detention were putting his safety at risk and hampering his ability to mount a defence, alleging there was ongoing misconduct by facility staff, such as disclosing his location number and prisoner ID to the news media.
Ms Burkart dismissed the arguments about his prison conditions as "hyperbole".
In particular, she mentioned one complaint relating to a delay of one day in receiving a Fedex package.
She said that "while he used to be a CEO, he is now a federal detainee", and a delay of one day in receiving a package was not a breach of his constitutional rights.
The court also heard how Mr Drumm's 80-year-old mother "had crossed the ocean" to visit her son on Christmas Eve and had been refused entry to the prison.
However the US Attorney said that Mrs Drumm had known she would not be able to visit her son due to visitation rules before she left Ireland.
The sitting judge also queried whether there were any similarities between the case of Bernie Madoff - the US investment banker convicted of the country's biggest ever fraud scheme - who had been granted bail and Mr Drumm.
Ms Burkart said there was not as there was a legal presumption against bail in extradition proceedings.
Judge Richard Stearns said that he was adverse to delaying matters, but that he needed "at least the weekend" to make a decision on whether to release Mr Drumm.
The extradition proceedings are currently set for 1 March.