The Fiji attorney general Aiyaz Sayed-Khaiyum has issued a High Court challenge after the Electoral Commission awarded a vacant parliamentary seat to Mikaele Leawere.
Mr Leawere took up a seat in March after the sudden death of the opposition SODELPA MP Ratu Viliame Tagivetaua.
The Commission awarded Mr Leawere the seat because he was the next highest polling SODELPA candidate in last year's general election, as required under the constitution.
But the attorney general believes the Commission erred because Mr Leawere was the acting general secretary of the Fijian Teachers Association at the time and the electoral decree says holders of public office are not eligible.
The Electoral Commission's lawyer Bhupendra Patel says Mr Leawere simply returned to his old job after he missed out on a seat in the election.
"Their submission that the intention of the electoral decree that once you become a candidate then you cannot go back to your old job contravenes the Bill of Rights, which has an entrenched provision now in Fiji for the first time. It gives a person the right to choose his own vocation, trade, occupation, what have you."
Bhupendra Patel says a decision from the High Court is due next Monday.