Well, for the Green Party it appears to be when you support nuclear power. The Independent says;
That's rather interesting.
Chris Goodall, prospective parliamentary candidate for Oxford West and Abingdon, upset many party members with his assertion in yesterday’s Independent that atomic energy has a role to play in the fight against climate change. Mr Goodall was one of four prominent environmentalists disclosed as having had a change of heart about the nuclear issue, having moved from an anti-nuclear stance to believing that atomic power is a necessary part of the energy mix in the struggle to cut carbon emissions and halt global warming.
The others are Lord Smith of Finsbury, the former Labour cabinet minister who now chairs the Environment Agency; Stephen Tindale, a former executive director of Greenpeace, and Mark Lynas, the author of two studies of climate change. But while the others are in essence free agents, Mr Good-all’s case is distinctive in that his views are now formally at odds with one of his own party’s key policy positions.
Resolute opposition to nuclear power has been a cornerstone of Green party policy for years, as is made clear in the party’s principal policy document, Manifesto for a Sustainable Society, which states unambiguously that a Green government, on taking office, would set a deadline for phasing out all nuclear power.
Mr Goodall’s remarks had left many party members “seriously concerned”, the Green Party leader, Caroline Lucas, MEP, said last night. “It is of great concern to me that a candidate should be promoting a policy which is at odds with the party manifesto, and I shall be taking that forward,” she said. “In any party, you have a range of different views, but once selected as a parliamentary candidate, you have a particular responsibility.”
The matter would be dealt with by the party’s regional council, after speaking to Mr Goodall directly, she said. Asked if this would include disciplinary action and possibly even de-selection as a candidate, Ms Lucas would only say: “We will be taking appropriate measures.”
My understanding is that the Green Party is a decentralised organisation and that elected members often differ from the party policy in one way or another. One example would be on Sir Ian Blair where one Green Assembly Member voted against sacking him whilst the other Assembly Member voted for and the national party was issuing press releases to the effect that he should go. I was never for that first member to be expelled despite being very frustrated by the whole thing.
Neither members rights nor nuclear power are mentioned in the primary document of the party and the constitution isn't particularly clear on this either so it's not obvious to me where the line should be drawn at all. The policy is clear that the party opposes nuclear power and one section states;
"Elected members and other representatives have a responsibility to promote the policies of the national and local green parties, as expressed in the MfSS and national, regional and local manifestos. Where they do not agree with Party policy and publicly state their own position, they should at the same time state and explain the position of the Green Party."As a PPC Chris is clearly a representative of the party and has clearly stepped over that line. He talks at length on the issue here and here and does not discuss the fact that he is at odds with party policy. But then the implications of this appear to be that any disagreement with the large number of policy documents is forbidden, except where you have the opportunity to explain your position in the context of the full party policy. That seems a bit much to me, and it's certainly a rule that many Greens break.
I don't agree with Chris on nuclear power - it's expensive, dangerous and will take too long to come on line anyway - but there is a genuine debate taking place in the environmental movement on this and I'd be concerned that he could not express himself freely on the issue. Mind you an open letter in The Independent is quite a high profile form of expression and I'm sure he expected some fall out from it.