MPs have heard that a bill to remove the rights of all prisoners to vote is irrational and abhorrent.
The Law and Order Select Committee is hearing submissions on the legislation.
At the moment, prisoners serving sentences of three years or more are disqualified from the electoral roll.
But a bill by National Party MP Paul Quinn, would deny voting rights to all prisoners.
Wellington human rights lawyer Tony Ellis says it is a purely punitive piece of legislation.
He told the committee it won't help rehabilitate prisoners, reduce crime or have any positive effect on prisoners.
Mr Ellis said the legislation breaches the bill of human rights and will place New Zealand in breach of its international human rights obligations
The committee is due to report back to Parliament by 21 October.