Welcome to Judges versus Executive, a fight as fierce as any Helen Clark has presided over in Cabinet, or Sian Elias in court. For nearly two years there has been unprecedented sniping between New Zealand's most powerful politicians and the country's top judge.

The Clark Cabinet, in particular Deputy Prime Minister Michael Cullen, has dubbed Elias a "judicial activist".

For her part, Elias has gone personal, criticising the Prime Minister for showing a "lack of understanding about judicial independence". She has complained in front of a British select committee over the funding, administration and very name of the Supreme Court, which last year replaced the Privy Council last year as New Zealand's highest appellate court.

And she has repeatedly warned international jurists of her fears that "judicial independence is at risk" in New Zealand.

There's more. Tussles over renovation proposals for a new Supreme Court building, judges' pay rates and superannuation schemes - issues that would seem petty if important principles were not at stake - earned Elias public scorn from former Attorney-General Margaret Wilson as the judges' "shop steward".

Conventions that have governed the relationships between politicians and the judges for decades and ensured mutual respect, at least in public, have been called into question.

At first glance it may seem like a personality clash between powerful forces led by two strong-minded women. But the clashes mask a real battle for supremacy in 21st-century New Zealand.

Elias would not be interviewed for this series. But she is on record - several times - as questioning the extent of Parliamentary sovereignty and has raised the possibility of a stronger role for the judiciary in New Zealand's constitution.

When tensions were high last year, Clark said judges should "stick to the bench" - if they chose to go into the political arena they would get a political response.

The Prime Minister remains adamant. "I always thought the issues she was drawing attention to were more minor administrative issues that didn't go to the heart of judicial independence, which must be upheld and fiercely protected." Clark is clear that the boundaries between the courts and parliament must not shift.

The seeds of growing discontent did not emerge publicly until the Court of Appeal's seabed and foreshore decision was made public in May 2003. The upshot was that the Crown could no longer assume it enjoyed ownership - iwi living next to the foreshore and seabed, who had continuously exercised customary rights since British settlement, might be able to establish a freehold claim.

The Government could have gone to the Privy Council, or waited to see how many applications to the Maori Land Court for customary use declarations were upheld.