The Labour Party leadership might very well feel like encasing errant Te Atatu MP Chris Carter in a block of concrete and burying him in the foundations of the new Victoria Park tunnel, but legally they can't. And if they stick to the Labour Party constitution, nor can they have him expelled from the party at this Saturday's meeting of the New Zealand council.

What's more, if party president Andrew Little continues to injudiciously mouth off about the sins of Mr Carter, he will have to stand aside from the disputes procedure outlined in the constitution. Otherwise he risks a court challenge for breaching the "principles of natural justice" that disciplinary procedures of the Labour Party require.

Party leader Phil Goff could reflect on what happened when the party left-wing majority plotted to have his colleague in the Lange Government, Auckland Central MP Richard Prebble, tossed out.

Mr Prebble took pre-emptive action and served legal notice on the whole NZ council that if they moved to expel him, he'd challenge the constitution in the courts. They backed off.

Yet compared with the guerrilla tactics used by both sides in the civil war that raged in the Auckland Central party organisation in the late 1980s and early 1990s, Chris Carter's school-girlish fit of pique against his leader was something of a love note.

I just can't believe that Mr Goff is, if not actually spelling it out, making it clear he wants Mr Carter expelled and that Mr Little is going along with it.

Expulsion is the ultimate weapon, saved for the grandest of crimes and misdemeanours. Off the top of my head, it's only been used once to discipline an MP in the party's near 100-year history. John A. Lee. It's not something to be used by a leader in a tit-for-tat spat over the passing-round of a rude note cheeking yourself.

Sources at Saturday's meeting of the Te Atatu electorate executive say Mr Little, who attended the crisis meeting, was warned of the potentially sticky road ahead by local party member Deborah Manning. Ms Manning, whose mother is one of two electorate secretaries in Mr Carter's constituency office, became a household name for her dogged and ultimately successful legal fight on behalf of Algerian refugee Ahmed Zaoui. Ms Manning argued that Mr Carter's actions had not been an attack on the party, it was a disagreement with the leader, which was not a matter for expulsion. With her Zaoui battle behind her, it was an open indication that the battle isn't going to be over by week's end.

The party constitution makes that clear. The NZ council can censure, ban from seeking or holding any office or candidacy and/or suspend a person's membership or expel them from the party for, among other things, contravening party rules, principles and policies and/or "bringing the party into disrepute". However, there is a procedure to follow and principles of natural justice to observe with a two-stage right of appeal.

So last Thursday, when Mr Goff told NZPA he doubted Mr Carter would remain a member of the party after a vote next Saturday, he was rather jumping the gun. Ditto Mr Little, who when told by NZPA that Mr Goff had asked that Mr Carter be expelled from the party, replied that "the case is pretty much there".

They might also contemplate the trouble former National Party leader Bill English got into when he suspended his critic, Pakuranga MP Maurice Williamson from caucus in 2003 and tried to have him expelled. Mr Williamson threatened a trip to the courts, and in the end the party suspended his membership only until the next election. It was a victory not for the leader but for the maverick.