"We think this is the archetypal sledgehammer and nut situation," she said.
Geiringer said the bill represented an undesirable and harmful extension of legal regulation into an area that was better controlled by political imperatives and electoral judgments.
There were some unscrupulous defections but very few since the early years of MMP because the political system dealt with it.
The bill was part of New Zealand First's coalition deal with Labour and critics say it will inhibit free speech and debate within parties and give party leaders too much power over MPs with dissenting voices.
It is still not known whether the Green Party, which has vehemently opposed a similar bill in the past, will support it beyond select committee.
The bill allows the effective expulsion of an MP from Parliament if the party leader, supported by two thirds of the caucus, writes to the Speaker saying the leader has reason to believe the MP has acted in a way to distort political party proportionality.
So long as the letter is delivered to the Speaker as stipulated under the law, a vacancy must be declared without inquiry.
Previous similar law, the Electoral (Integrity) Amendment Act 2001, had a time limit and expired in 2005. Attempts to extend its limits beyond 2005 failed.
Submissions today were overwhelmingly opposed to the bill, including those from former Green MP Keith Locke, electoral expert Graeme Edgeler and some major concerns were voiced by the Law Society such as whether it could invite judicial review of caucus discussion.
Locke said the bill demeaned Parliament by treating MPs like robots or voting fodder.
The whole point of debate in the parliamentary chamber was to try to persuade MPs to change their minds, to convince them "that our policies are best".
"But if an MP from another party actually changes his or her mind, as a result of parliamentary debate, this bill will silence them," he said.
"In real politics, parties can change their policies to the point of alienating some MPs; MPs can change their view and parties can split over how to address a new political situation – as the Labour Party did in 2004 over the Foreshore and Seabed."
The constitutional and legal experts
This joint submission is from a group of 19 legal academics and political scientists, whose area of research speciality includes constitutional law, electoral representation and parliamentary practice:
• Natalie Baird, University of Canterbury School of Law.
• Dr Fiona Barker, Victoria University of Wellington School of History, Philosophy, Political Science and International Relations.
• Dr Eddie Clark, Victoria University of Wellington Faculty of Law.
• Dr Joel Colón-Ríos Victoria University of Wellington Faculty of Law.
• Professor John Dawson, University of Otago Faculty of Law.
• Professor Andrew Geddis, University of Otago Faculty of Law.
• Professor Claudia Geiringer, Victoria University of Wellington Faculty of Law.
• Professor Janine Hayward, University of Otago Department of Politics.
• Professor Philip Joseph, University of Canterbury School of Law.
• Dr Dean Knight, Victoria University of Wellington Faculty of Law.
• Dr Lindsey Te Ata o Tu MacDonald, University of Canterbury Department of Political Science and International Relations.
• Adjunct Professor Elizabeth McLeay, Victoria University of Wellington School of History, Philosophy, Political Science and International Relations.
• Dr Kate McMillan, Victoria University of Wellington School of History, Philosophy, Political Science and International Relations.
• Sascha Mueller, University of Canterbury School of Law.
• Steven Price, Adjunct lecturer, Victoria University of Wellington Faculty of Law.
• Marcelo Rodriguez Ferrere, University of Otago Faculty of Law.
• Leonid Sirota, Auckland University of Technology Law School.
• Professor ATH Smith, Victoria University of Wellington Faculty of Law.
• Dr Claire Timperley, Victoria University of Wellington School of History, Philosophy, Political Science and International Relations.
