BBC political correspondent Nick Jones explains the lord chancellor's role in government and why he is in trouble over fundraising.

Q: Who is the lord chancellor?
A: Lord Irvine of Lairg, formerly Alexander Andrew Mackay Irvine and known as "Derry" to his friends, was appointed lord chancellor by Prime Minister Tony Blair after Labour's general election victory in May 1997.

Lord Irvine was head of the legal chambers where Tony and Cherie Blair worked as barristers and he is godfather to one of the prime minister's sons.

Q: What is the lord chancellor's role?
A: The main job of lord chancellor is to be, in effect, the minister of justice for England and Wales.

The role is unique and controversial in British politics because the office holder has power in three key areas of the constitution - the government, the legal system, and parliament.

The lord chancellor is a senior member of the cabinet and is in charge of his own government department. As such, he is usually a senior member in the governing political party.

At the same time, he is head of the independent legal system and is responsible for the management of the courts, appointing magistrates and judges, and deciding who should become QCs.

And thirdly, he is a vital part of the British parliament where he presides over the House of Lords. But there's no grand throne-like seat for the lord chancellor like the speaker's chair in the Commons.

Instead, Lord Irvine perches on a very large red cushion, known as the Woolsack. In a tradition dating back to the time of Edward III, this is stuffed with wool and served originally as a reminder that Britan's prosperity depended on the wool trade.

The post of lord chancellor dates back even further, at least to the 11th century, and is therefore older than parliament itself. The Lord Chancellor's Department has a budget of nearly �2.5 billion this year.

Q: Why is Lord Irvine in trouble?
A: The Conservatives insist Lord Irvine has failed to be "impartial and non-partisan" by writing to Labour-supporting barristers and solicitors inviting them to pay at least �200 to attend a fundraising dinner for the party.

Lawyers who received the letters were put under pressure to contribute because of the lord chancellor's power of appointment, say his critics.

Q: How do people suggest the system should be reformed?
A: Various bodies including the Law Society have called for an independent judicial appointments commission to replace the lord chancellor's powers to appoint judges and QCs, in order to eliminate any question of bias. Judges, practising lawyers, academics and lay people would sit on the panel.

A government-funded report from the Economic and Social Research Council last year was the latest to call for the post of Lord Chancellor to be abolished altogether and replaced by a minister of justice, accountable to the House of Commons.

Q: Does Lord Irvine agree?
A: No. He made a speech in 1999 saying the lord chancellor remained "a bulwark of our constitution" and an invaluable buffer between the executive and judiciary.

With the current system, the lord chancellor holds together all three parts of government and "withstands pressure from all sides", he said. His triple role also means the judiciary is accountable to parliament through him in the House of Lords, he added.

The Labour Party pledged in its 1992 election manifesto to abolish the lord chancellor's office but has backtracked on that policy in recent years, not least since being elected to government.

Q: How much is the lord chancellor paid?
A: The annual salary is �173,875 from April, the highest in government because it is based on legal rather than ministerial scales.