Judges have been told by Attorney-General Michael Cullen to point out deficiencies in law in their judgments rather than try to change the law through judicial activism.
In his first big speech since becoming Attorney-General in February, he reasserted his view of the supremacy of Parliament over the courts, saying that their independence did not give them American-style powers to strike down legislation or alter it if it was found wanting.
He said that except in very limited and special circumstances, such as correcting minor drafting errors, "no mandate exists for fixing such deficiencies outside of an elected Parliament".
But he said there were occasions when the courts could not be criticised for having been judicially active.
He cited the Lands case of 1987 in which the Court of Appeal defined the principles of the Treaty of Waitangi as being "partnership".
Parliament passed an act referring to the principles without defining them in the State-Owned Enterprises Act 1986.
"The fact is that Parliament did ask the courts to perform that role and the courts cannot fairly be criticised for doing as Parliament required," he said in a speech to the Legal Research Foundation in Auckland.
It was not a sign of "improper judicial activism".
However, nor is it a sign that Parliament intends the courts to undertake the same task for all legislation.
It did not, as a rule, deliberately leave loose ends in legislation for the courts to tidy up.
Dr Cullen said he was entirely happy for judges to point out deficiencies in the law when deciding cases before them.
But they had no mandate to fix the deficiencies.
"Any perception that the courts are taking upon themselves this responsibility has the potential to undermine public confidence in their role and in their independence from the political process."
The speech revisits his challenge last year to Chief Justice Dame Sian Elias, who had questioned the notion of the sovereignty of Parliament.
He said that expectations that sparks would fly across Molesworth St - where the courts sit - had so far been disappointed. He believed he had a very amicable relationship with the judiciary - he now meets Dame Sian once a month.
Part of his role was to defend the integrity of the justice system.