Justice could be under "grave threat" from proposed legal aid cuts, according to barristers.
Hundreds of barristers, solicitors and law students are set to come together at the protest event - titled One Bar: one voice - United for Justice - at Lincoln's Inn in central London. It has been organised by the Bar Council, which represents barristers in England and Wales, who fear it will endanger vulnerable people in need of high quality legal representation.
Nicholas Lavender QC, chairman of the Bar who is among the event speakers, said: "This is a vital opportunity to demonstrate that the whole profession stands together in support of the Rule of Law and access to justice, which are under grave threat from the Government's proposed cuts."
The Ministry of Justice has said it was vital to scale back the most expensive legal aid scheme in the world and insisted it will remain ''very generous'' even after the changes.
The department highlighted figures showing that 1,200 barristers judged to be working full-time on taxpayer-funded criminal work received £100,000 each in fee income last year. Six barristers picked up more than £500,000 each, it said.
The Bar Council sees the meeting as the profession's last chance to talk through its concerns on a big scale before the Ministry of Justice (MoJ) announces the outcome.
Speakers also include Nigel Lithman QC chair of the Criminal Bar Association, former president of the London Criminal Courts Solicitors' Association Paul Harris, Timothy Fancourt QC chair of the Chancery Bar Association and Susan Jacklin QC chair of the Family Law Bar Association along with Martin Westgate QC of the Constitutional and Administrative Law Bar Association.
Mr Lavender said: "The Government says that it needs to make savings, but the proposed cuts to the fees paid for advocates in the Crown Court are both unnecessary, because legal aid costs are falling anyway, and a false economy, because they will end up generating more costs than they save. Under the Ministry of Justice's (MoJ) plans, these cases would no longer be conducted by the skilled and experienced advocates on whom our criminal justice system depends, and the publicly-funded Bar of the future would be significantly less diverse, resulting in less diversity in the judiciary in years to come. The greatest victims would be the public interest and the society which we seek to serve.
"What is more, these cuts endanger our outstanding international reputation for upholding the Rule of Law. The damage which these cuts would plainly do to our domestic system would have a wide-reaching and global effect on a legal services sector which generates billions of pounds of revenue for our economy each year.
"It is not too late for the MoJ to reflect on the damage which its cuts will cause and to review the justice system sensibly and properly with the profession, so that we can achieve savings whilst maintaining access to justice."
A Ministry of Justice spokesman said: "At around £2 billion a year we have one of the most expensive legal aid systems in the world, and it would remain very generous even after reform.
"We agree lawyers should be paid adequately for their work and believe our proposals do just that. We also agree legal aid is a vital part of our justice system - that's why we have to find efficiencies to ensure it remains sustainable and available to those most in need of a lawyer.
"We do not underestimate the challenge reform presents for lawyers but there is severe financial pressure that makes it necessary. We are examining every area of the department's work to find savings - legal aid has not been singled out."
The meeting takes place at the Great Hall, Lincoln's Inn, central London, at 9.30am.