Senator Ivor Callely should not have been suspended from the Seanad over an expenses scandal, the High Court ruled today.
The former Fianna Fail politician, who resigned from the party last year, successfully challenged a Committee over his 20-day ban from the upper house over his mileage claims.
The Seanad inquiry was found to have breached the Senator's right to justice and fair procedures.
Judge Iarfhlaith O'Neill found the Committee did not allow Mr Callely a reasonable opportunity to defend himself on political ethics charges.
"On the basis that the respondent failed to exercise their adjudicative function in an appropriate judicial manner by making a political judgment on the issues in the investigation, thereby breaching the applicants constitutional rights and fair procedures," the judge ruled.
"They misdirected themselves in law on the definition of normal place of residence."
Mr Callely, whose political base was Clontarf, north Dublin, claimed €80,000 for travel from his holiday home in Kilcrohane, west Cork, over three years.
The parliamentary probe by the Seanad committee last July found that the scandal-hit Senator deliberately misrepresented his normal place of residence as being the holiday home, rather than Dublin.
Mr Callely took his case to the High Court in a bid to quash the findings of the investigation and overturn his ban, without pay, from the Seanad.
Mr Justice O'Neill said this was the first time a member of the Oireachtas had come to the High Court to challenge a decision of a committee of a House of the Oireachtas.
The judge found that the Senator was right to take the case to court as his only other route of appeal was through the Oireachtas system which punished him.