In theory, Labour's policy of managing immigration seems eminently sensible. The party would, said David Cunliffe, aim for "a steady, predictable, moderate flow that's at a level that addresses skill shortages". In reality, however, such an approach is impractical. New Zealand has had enough experience with stop-go immigration policies to know that while it might be easy to turn off the tap, it can be extremely difficult to return the flow to the desired level.
The issue has leapt to prominence after Treasury figures in last week's Budget forecast annual net inward migration would peak at 38,000 this year, but could be as high as 41,500. This was accompanied by a warning that the rising numbers could further fuel the high cost of housing.
Labour says that threat could be defused by restricting the annual migrant intake to between 5000 and 15,000. It did not dwell on how that would affect the external perception of a policy that could no longer be said to be stable, sage or welcoming.
Perhaps the foremost flaw in Labour's approach is the considerable difficulty of tailoring immigration to skill shortages. The lag between a policy being announced, its implementation and its outcome is too great to guarantee anything approaching success.
Unexpected events, of whatever nature, can quickly render it foolish. Most importantly, the result can be an unnecessary shortage of skilled workers in a particular area when demand changes. They will have been lost to other countries.