A submission made from a group of 19 legal academics and political scientists concluded that the amendment was a breach of the Bill of Rights.
The amendment could potentially see MP's removed from office despite receiving the public vote, something Nick Smith called "an attack on basic democratic values and centuries-old freedom of speech."
National’s Electoral Law Spokesperson Nick Smith said “This chorus of condemnation from such a large group of political and legal academics shows what a dog this bill is. It is unprecedented for so many experts to come out so united against a Government electoral law change."
He added that "it will harm our democracy and will give party leaders too much power."
Smith said it's a crude power grab by Winston Peters to give him absolute power over his MPs in this fragile government, but which dangerously converts New Zealand into what the Inter-Parliamentary Union calls a party dictatorship.
National said they will oppose the bill at every step.