We are seeing a worrying increase in attacks on the judiciary by MPs, under the guise of protecting parliamentary sovereignty.

Michael Cullen's recent criticism of 'judicial activism' is just the latest. In September last year Act MP Stephen Franks accused Chief Justice Sian Elias of bias over the foreshore and seabed. Apparently, as a lawyer, she had previously represented Maori litigants, in particular in the 1985 Manukau Harbour case.

More significant was the Prime Minister's attack on Maori Land Court Judge Caren Wickliffe in March this year. Helen Clark accused the judge of bias after she allowed a coastal claim to proceed to a hearing even though the Government had signalled its intention to pass new legislation, and an appeal to the Privy Council on the earlier Marlborough case was underway.

It would be quite wrong for judicial decisions to be made on the basis of the Government's stated intentions. The judges' role is to interpret the law as it is before them, not to second-guess parliament.

Similarly, Mr Franks' criticism of the Chief Justice ignores the reality that all judges have, at one time or another, represented many different clients and that their resulting expertise is crucial to their ability to judge.

It is a concern that political disagreement with a judge's decision can lead to accusations of partiality. Such criticisms are, in my opinion, misinformed.

Law Society President, Christine Grice, criticised Mr Franks' comments as inappropriate and wrong, warning that: "having not been put in issue in the proceedings, an allegation of actual bias by a person in a privileged position, knowing that the Judiciary will not respond, could seriously harm the integrity of the Judiciary".

If these cases are the basis of Dr Cullen's accusations that judges are 'making law', it represents flimsy evidence. In fact, both cases can be seen as judges upholding the law in the face of political demands to do otherwise. Judges' obligation, after all, is to the rule of law, not to Parliament.

Such a view may have been behind the Chief Justice stating recently that "an untrammelled freedom of Parliament does not exist". It would see our constitutional checks and balances as a dynamic system of responsible governance rather than a competition for absolute power.

Having a unicameral (single house) system without a written constitution has meant that historically parliamentary sovereignty has been asserted, in particular by MPs, but has rarely been publicly challenged. However the New Zealand Parliament is unusual in its claim of unlimited legislative power.

Most countries have a constitution or charter that constrains the legislature, as well as an upper house which acts as a brake on hasty decision-making. Even Westminster itself recognises the European Convention on Human Rights and the jurisdiction of the European Court of Human Rights in Strasbourg. In fact, the recent UK 'Proceeds of Crimes Act 2002' may soon run into difficulty there.

It is in the area of human rights that constraints on Parliament are so essential. Recent events in the prisons of Iraq and at Guantanamo Bay clearly demonstrate what can happen, even in a nation that prides itself as the guardian of democracy, when elected decisionmakers take a casual view of human rights.

Sir Geoffrey Palmer has said in 'The Laws of New Zealand' that some judicial decisions suggest that: "some common law rights, such as the right not to be subjected to torture and the right of access to the Courts, may lie so deep that not even Parliament can override them."

I am not convinced that New Zealanders would agree with Dr Cullen that such rights can be legitimately removed by Parliament. Even Cullen himself has acknowledged some constraint on Parliament when he told the Labour Party in March that the Treaty of Waitangi is "a document that can scarcely be unilaterally abrogated by the Crown".

Dr Cullen is referring to the more limited rights affirmed in the English version. When we consider that the Maori language version, signed by Governor Hobson and most of the rangatira, did not cede Maori sovereignty, the 'unrestricted sovereignty of parliament' becomes an even more tenuous concept.

In practical terms, however, it is unlikely that a New Zealand Parliament would, any time soon, give the courts cause to challenge its right to legislate. In that sense, while the current discussion is important and interesting, any threat to parliamentary sovereignty from the judiciary is largely academic.

A greater threat to parliamentary sovereignty comes from the concentration of power in the hands of the Executive. MMP has limited that somewhat, but the ability of the Executive to, for example, sign international treaties by Crown prerogative without any regard to Parliament remains.

On the other hand, attacks on judges by parliamentarians do threaten the real world independence of the judiciary. With our final court of appeal moving home, in the Supreme Court, such attacks are particularly concerning.

During the passage of the Supreme Court Act last year the Greens extracted a commitment from the Government to a public debate on the way judges are appointed. As a result, in April this year the Government released a discussion document on an independent judicial appointments commission.

Such a body is one way of avoiding the politicisation of the judiciary that Dr Cullen has warned against. Interestingly such a proposal is also under discussion in the UK where, I am told, the judiciary itself is partly driving the initiative.

While the establishment of a transparent process for judicial appointments will not protect judges from political attack, when put alongside the new judicial complaints process, it should help to limit them and to ensure that criticisms can be properly answered.