Criminal barristers in England and Wales voted to go on strike on an "indefinite basis" from September 5.
A dispute over pay, working conditions, and legal aid funding has led to members of the Criminal Bar Association (CBA) to take strike action on alternate weeks until now.
By a majority of 79.54%, nearly 2,300 members of the CBA voted in favour of escalating their action to a permanent strike over criminal legal aid rates from September 5.
Many cases will be delayed by the strikes, which will prolong the justice process for victims and accused.
Courts in England and Wales are already dealing with a large backlog of cases in part due to the pandemic, with HM Courts and Tribunal Service figures showing 58,271 cases awaiting trial at the end of April.
The CBA is seeking a 25% pay raise for legal aid work when they represent defendants who cannot afford lawyers.
It is expected that criminal barristers will receive a 15% fee rise at the end of September, with the Ministry of Justice reporting that the average lawyer will earn an extra £7,000 a year as a result of the increase.
The CBA, however, rejected the government's pay offer, saying it would not kick in immediately or apply to existing cases.
Government data shows 6,235 court cases - including 1,415 trials - were disrupted during the first 19 days of industrial action between June 27 and August 5.