Demonstrators will descend on the Royal Courts of Justice this week to mark the launch of a campaign group that wants to see the Lord Chancellor booted out of Cabinet.

The Campaign for a Fair Hearing is an umbrella organisation, set up by Action for Justice, which is pressing for complete separation of powers between the judiciary and the executive, and an end to parliamentary sovereignty.

It plans to hold weekly gatherings outside courts throughout the UK in a year-long campaign aimed at raising awareness and initiating debate. The first meetings will take place this Wednesday.

The group argues that the judiciary is not independent of government and so cannot safeguard human rights.

It is calling on the Government to transfer the Home Secretary's quasi-judicial powers to the head of judiciary and to use a Transfer of Functions Order to separate the Lord Chancellor from the Cabinet.

It also wants to see an end to the theory of parliamentary supremacy, which stops citizens from challenging the legality of statutes in court. “If the Government wants to be respectable it can't deny people basic human rights,” said campaign organiser Suzon Forscey-Moore.

Earlier this summer, Lord Mackay defended his dual role as head of the judiciary and Cabinet member, in a speech to the Citizenship Foundation.

“It may be suggested that a stricter separation of powers would be preferable. When looked at practically, it emerges not only that there are weaknesses in such a rigid approach but also that there are great strengths,” he said.