More than 16,000 court and Crown Prosecution Service workers will stage a one-day strike on Monday, as campaigners against various government reforms step up their attack.
Around 2,500 CPS employees who are members of the Public and Commercial Services Union will stage industrial action on Monday morning.
In the afternoon, a further 14,000 members working for the Ministry of Justice, Cafcass, Criminal Cases Review Commission, Judicial Appointments Commission, the Parole Board and Youth Justice Board will also walk out.
The strike will coincide with a protest planned in Manchester on the same day, jointly co-ordinated by local lawyers and the PCS.
Campaigners will meet at 1pm outside the Civil Justice Centre in Bridge Street to protest about plans to cut legal aid funding and restrict choice for clients needing legal representation.
Earlier today, a petition designed to oppose government proposals for price-competitive tendering passed 90,000 signatures.
The PCS action is the latest in a series of rolling strikes this month over cuts to pay, pensions and conditions.
PCS general secretary Mark Serwotka said: 'These workers provide vital services every day across our justice system, and they do not deserve to be shunned by ministers who are refusing to even talk to us about the cuts they are imposing.'
The report concludes that £2bn of cuts across the justice sector - representing 23% of the MoJ budget - will have a 'devastating effect' on the administration of justice. It added that 15,000 justice sector jobs are expected to be axed by 2015.
An MoJ spokesperson said: 'At £2bn a year we have one of the most expensive legal aid systems in the world and must ensure we get best value for every penny of taxpayers' money spent.
'We have just finished consulting on a number of proposals to reform legal aid and are now carefully examining all the responses. Quality, professional lawyers would still be available to anyone needing advice or charged with a crime just as they are now.'