Legislation under which an MP would lose their seat if they switched parties during a parliamentary term has been introduced to Parliament.
The so-called 'waka-jumping' legislation is part of the coalition deal between Labour and New Zealand First.
Under the bill, in the name of the Justice Minister, Andrew Little, list MPs would be out of Parliament altogether if they left the party under whose banner they were elected.
Electorate MPs would lose their seat but could seek a return to Parliament through a by-election.
When agreement was made for this law to be introduced, the New Zealand First leader Winston Peters said it was a matter of principle that MPs should not betray the party that put them in Parliament.