The State’s Criminal Legal Aid Scheme ran €5 million over its allocated budget last year.
The total expenditure was €53 million, with an allocated budget of €47.6 million last year, figures released by the Department of Justice to The Irish Times under the Freedom of Information Act show.
Criminal legal aid is free and is provided to those facing criminal charges who pass a basic means test. Given the high costs involved in defending even basic criminal charges, a majority of people facing such charges in Ireland are entitled to aid.
The department said the demand-driven nature of the criminal legal aid system makes it difficult to control costs.
Parties in high-profile and long-running cases, such as former Anglo Irish Bank chairman Seán FitzPatrick and Solidarity TD Paul Murphy, have been granted legal aid in the recent past.
The Criminal Justice (Legal Aid) Act 1962 states that people of “insufficient means” have a constitutional right to free legal aid in certain circumstances in criminal proceedings.
Legal aid is granted in all courts, including the District, Circuit and higher courts. The Department of Justice has no involvement in the granting of criminal legal aid or the assignment of solicitors.
Under the scheme, services are provided by private solicitors and barristers who have given notification of their availability to undertake such work.
Fianna Fáil justice spokesman Jim O'Callaghan said: "At a time when there is a lot of demand on resources, it is important that the legal aid bill is kept under control. Although it is a demand-based cost, it cannot be allowed in the future to exceed budget by these levels."
In total, solicitors and barristers received just under €29.3 million through the scheme last year.
The legal practice operated by solicitor Cahir O'Higgins received the highest amount in such payments last year, at €464,865 (including VAT). Michael J Staines received the second-largest amount (€451,011), followed by Frank Buttimer (€447,374).
The best-paid barrister in the country last year through criminal legal aid was Michael Bowman SC, who only became a senior counsel in 2015. Mr Bowman received €478,557.