Scandal-hit Senator Ivor Callely has been wrongly portrayed as a thief, his lawyers claim.
The High Court was told the former junior minister has suffered disastrous consequences since an inquiry into his controversial expenses and subsequent 20-day Seanad ban.
His lawyer said a parliamentary probe found Mr Callely committed an unethical act deserving punishment but nothing dishonest.
The senator, who walked out on Fianna Fail last month, is suing a seven-strong Seanad committee for loss of earnings after they barred him from taking his seat.
Michael O'Higgins, lawyer for the suspended senator, told the court the publicity around the inquiry was used as a plinth to launch one of the most vitriolic attacks ever seen on a politician.
Michael O'Higgins, senior counsel, said it was wrong of the Seanad Committee on Members' Interests to portray that Mr Callely had intentionally misrepresented his normal place of residence when lodging expense claims.
He maintained this was reported "as an example of a politician in effect stealing from the system" and followed with a huge clamour for Senator Callely to be brought to a criminal court and indicted for his dishonesty.
"It was used as a plinth to launch some of the most vitriolic attacks seen by a politician elected by the people and who was entitled to a measure of respect," said Mr O'Higgins.
Mr Callely, whose political base was Clontarf, north Dublin, claimed 80,000 euro (£67,000) for travel from his holiday home in Kilcrohane, west Cork, over three years.
He is challenging an inquiry by the Seanad committee which found he deliberately misrepresented his normal place of residence as being the holiday home, rather than his house in Dublin, and suspended him for 20 days.