Criminal barristers are striking at 16 courthouses around the country, demanding the reversal of pay cuts imposed on them in the aftermath of the financial crisis.
Hundreds of members of the Bar of Ireland who practise in criminal law are taking part in the protest.
They first withdrew their services in October, in an unprecedented action. In the subsequent budget, the Government agreed to increase fees of criminal barristers and solicitors by 10%.
However, the barristers say that does not fully restore the cuts imposed since 2008 and they say the breaking of the link with public sector pay agreements has still not been restored.
They also say, despite a commitment from Minister for Justice Helen McEntee a promised review process looking at the structure and level of fees paid has still not begun.
Chair of the Council of the Bar of Ireland Sara Phelan said the frustration among criminal barristers was absolutely palpable.
She said they had one meeting with the Government in relation to fees since October and that was "too little, too late". She said they needed progress fast.
Senior Counsel Sean Guerin, who is chair of the Criminal State Bar Committee of the Bar Council, said barristers regretted being out on the steps.
He said they were not looking for a pay rise - simply an unwinding of cuts imposed in the financial emergency.
Today’s action has led to hundreds of trials being adjourned.
People who had been called for jury service arrived at the Criminal Courts of Justice to be sent home and some expressed their annoyance at being inconvenienced.
In the Circuit Criminal Court, trials were adjourned with some solicitors in court to take a note of the adjourned dates. The Central Criminal Court did not sit at all today and trials will resume tomorrow.
The Minister for Justice said in a statement that she will seek to make further progress in the upcoming budget in relation to the restoration of fees. But she said the budgetary process must be followed.
Criminal barristers say they intend to go ahead with two further days of action planned for 15 July and 24 July.

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Speaking on RTÉ’s Morning Ireland, Mr Guerin said barristers have not had their pay cuts restored despite them having co-operated with changes in the justice system.
He added that barristers have co-operated with "significant improvements in flexibility and reform" in the criminal justice system since 2018.
"And in doing so, have met the condition for restoration of the temporary pay cuts.
Mr Guerin noted that Minister McEntee has said "there is no good reason why pay restoration hasn't taken place.
"We have been waiting now since 2016, but at least in 2018 it was acknowledged that we had met the conditions for pay restoration.
"There's no good reason why the Government couldn't now give a commitment to resolve this long outstanding issue, this long, outstanding unfairness, and implement it in the budget.
"We're not looking for a pay increase. We're looking for simply FEMPI-era pay restoration," he said.

Criminal law barristers in Cork have described what they say is their sense of frustration over the failure of Government to reverse the pay cuts and say while they do not want to withdraw their services, they feel they have no option at this stage.
Senior Counsel Tom Creed, who practises in both Dublin and Cork, said the protest is as much about the future of the criminal justice system as it is about their own pay.
"I have been doing this for 40 years. This is not about me - this is about young people coming to the bar and making a sustainable living at the criminal bar. We believe it is vitally important for our criminal justice system," he said.
Speaking outside the courts complex on Washington Street in Cork, Mr Creed added: "If we don't look after our criminal justice system I believe it will fall asunder, like what's happening in the UK at the moment. You will recall, they had an all-out strike there, but they are in a situation where they can't get prosecutors to prosecute some cases. We don't want that. We believe in the criminal justice system, but it must be sustainable.
"We are losing young barristers after five years. 50 to 60% are gone. The DPP will only employ experienced barristers so, unless it is sustainable, unfortunately, people who want to practice at the the criminal bar won't be able to do it. They are the people I am concerned about."

Paula McCarthy has been practising in Cork for the past 16 years and said she does not want to be protesting, but feels she does not have a choice.
#"We don't want to deny people justice. We don't want to deny people representation. We don't want to put victims in a situation where they are not being heard. But we feel we have no possible option but to do this, because we are not being heard," she said.
Ms McCarthy added: "We were told on 23 October that there was going to be meaningful engagement and, in fact, nothing has happened since 23 October. We have been left with no option but to do this in order to get engagement from the Government."
Additional reporting Paschal Sheehy