The Law Society says a bill which could inadvertently lead to prisoners again being able to vote, was sent to the wrong parliamentary committee.
Under current law, prisoners serving a sentence of more than three years are not allowed to vote.
The Law and Order Select Committee is considering a bill which seeks to disenfranchise all prisoners.
The committee has recommended repealing the relevant section of the Electoral Act and replacing it with a provision that would mean the law applies only to those sentenced after the 2010 amendment was passed.
The Law Society says the bill should have gone through the Justice and Electoral Select Committee instead.
President Jonathan Temm says there is an error with the bill as it is and it will have to go back to be reviewed.
The bill's sponsor, National MP Paul Quinn, says the bill was correct when he sent it to the select committee.
He says if there is a mistake with it, it can be fixed through the supplementary order process.