Every law student knows that there is only one person in this country who belongs to the executive, the legislature, and the judiciary: the Lord Chancellor. But should the status quo survive? Or, indeed, will it?

In May 2001, the Parliamentary Assembly of the Council of Europe called on the UK to review the Lord Chancellor's office so that his judicial function is no longer combined with membership in the Cabinet and presiding over the House of Lords. While a final assembly resolution is pending, let us ask: do we want the present system – this constitutional accident – to carry on?

The answer should be 'no'. The rational arrangement must be for the House of Lords to choose its own speaker, for the Law Lords to become a supreme court that is independent from the legislature and the executive, and for a minister of justice, who is not the head of the judiciary, to deal with the justice system.

The debate is about the office, not the man. Certain powers go with the office, including the right to choose who sits on appeals in the House of Lords, the right to sit as a judge, and the right to be the man who represents the judiciary in the Cabinet and the Cabinet in the judiciary. Each Lord Chancellor exercises those powers as he thinks right.

The job has become all the more daunting as the Lord Chancellor's Department (LCD) has grown exponentially since 2001. Under the new Courts Bill, the entire court system will be the Lord Chancellor's direct responsibility, and he will have the power to appoint all judges, magistrates, court officers and staff, down to the new fines officers and court security officers. When the magistrates' courts are absorbed, the LCD will employ some 25,000 staff. It also has responsibility for all tribunals, constitutional issues, judicial appointments, royal and church issues, the Legal Services Commission and the Community Legal Service, policy on criminal, civil and family law, the Land Registry, freedom of information, data protection, the Public Record Office, devolution issues, social exclusion, and much more. The present Lord Chancellor sits on 11 Cabinet committees and chairs four of them. He hasn't sat on an appeal in more than two years, not because he doesn't want to, but because he doesn't have the time. Still, no one benefits from retaining a function for the sake of it.

There are arguments about the effect of Article 6 of the European Convention on Human Rights (the right to a fair trial), and about transparency. Many of the present arrangements appear to rest on assurances and guidelines. The Law Lords remain in the legislature in part so they can assist on some legislation, and they receive advice on when and how to take part in debates so as not to prejudice their ability to sit on future appeals. This is far too convoluted. It is simply not the role of serving judges to help to make statutes. The most recent example of a clash between the executive and the judiciary came when Mr Justice Collins ruled against the Government's new legislation on immigration and asylum. The Home Secretary complained on Radio 4 that he was tired of Parliament passing laws only for judges to say that they were wrong. The Lord Chancellor may disapprove when ministerial colleagues criticise judges whose judgments go against the Government, but it is something he would normally express to the minister only in private. The public is still left with the impression that judges are frustrating the will of Parliament and hence, of the electorate. A Lord Chief Justice with an enhanced role might speak out. How the Lord Chancellor is required to represent the Cabinet to the judiciary is anyone's guess.

When the Rapporteur of the Assembly of the Council of Europe appeared before the Committee of the Lord Chancellor's Department, he was accused by an MP of ignoring UK culture and history. Lord Irvine told the committee that we are a nation of “pragmatists, not theorists… we go for what works”. He rejected the idea that Article 6 is about our constitutional arrangements.

Let us honour UK culture and its chief virtue, which is good sense. Purely on pragmatic grounds, let us set up a system in which justice and the separation of powers is not only done, but is seen to be done.