The return of Parliament tends to lower the tone of political discussion and harm the quality of government. Until the House reconvened this week the Prime Minister sounded intent upon an "elegant" settlement of differences with the Maori Party over the application of a Treaty obligation to state power companies the Government wants to float on the sharemarket.
Now, he is driven to remind the opposition he has the numbers to pass asset sale legislation without the Maori Party's support.
Maori, meanwhile, have filed a claim with the Waitangi Tribunal, seeking ownership of the water used by the electricity generators. To that, the Prime Minister retorted, "no one owns water. It's like air," he said. "No one owns air."
As a correspondent on the Herald letters page asks today, who is paying John Key's water bills? Fresh water in lakes, rivers and aquifer is not like air, it is a limited resource, capable of being owned, controlled, dammed or distributed in piped or bottled form for countless profitable purposes.
Mr Key will need to find a better answer to this latest challenge to asset sales.
The Maori Council's lawyer, Donna Hall, concedes the Crown has steadfastly refused to acknowledge a proprietary claim to water, notably by Tainui who had to settle for a "guardianship" status over the Waikato River. Others point out that the Waitangi Tribunal is unlikely to revisit settlements so recently and solemnly made by Tainui and Ngai Tahu, whose domain includes the South Island hydro lakes.
The tribunal could take a long time to decide that it will not hear the case, and its rulings cannot bind the Government to act in any case. But this is not an issue that needs to be decided by crude power. The Government's programme of partial asset sales is not so urgent or vital to the economy that it needs to ride roughshod over all other concerns.
The Maori Party was understandably concerned when it realised the Treaty obligation expressed in section 9 of the State Owned Enterprises Act 1986 would not apply to the floated companies.
The implications of the section may be unclear and unwelcome to any commercial enterprise, but they are not fatal to this asset sale. The stock of state-backed companies will be keenly subscribed because they are underpinned by the taxpayer. It is perfectly reasonable, therefore, that subscribers accept the company's state obligations in return for that security.
And one of the state's most important obligations is to honour the spirit of the Treaty on which it was founded. That means listening to Maori when important decisions are made, acknowledging their interests and accommodating them where possible.
State-owned enterprises are already supposed to do this and it does not seem to have inhibited their commercial operations at all. Public-private partnerships can do the same.
There has been no better example of this co-operation than most of Mr Key's dealings with the Maori Party so far. Now the Maori have put his partnership to its most severe test.
The party threatens to withdraw its support if a Treaty obligation is not transferred to the partially privatised companies. This issue is much more important for the Maori Party and its standing with its people than it is for the fate of the asset sales programme.
The Prime Minister has the numbers to sideline Maori on this issue if he wants, but he would do so at a price. His Government would lose a dimension that has offered something hopeful.
He should not let parliamentary taunts and threats of litigation lower his sights or confuse the issue. It is not about water, electricity or even ownership, it is about participating in decisions.