The number of magistrates in Gwent has fallen by nearly 25% over the past three years, in line with the national average.
An independent charity is warning that dwindling magistrate numbers could have an impact on the administration of justice.
Figures from the Courts and Tribunals Judiciary show that there are 177 magistrates currently sitting in the area, compared with 230 three years ago.
Magistrate numbers are falling significantly across England and Wales, from nearly 20,000 magistrates in 2015 to just over 15,000 this year – a drop of around 25%.
The Magistrates Association has said that it is increasingly hearing from its members that magistrates are sitting in benches of two, rather than three, including during trials – due to shortages and magistrates needing to drop out.
Magistrates Association chief executive Jon Collins said: “Three people will always be able to make better decisions.
“These situations should not be normalised, particularly for decisions of innocence or guilt.”
Mr Collins said that for magistrate numbers to remain constant over the next ten years, more than 8,000 new magistrates need to be recruited to replace those retiring once they turn 70.
“But we think we need to recruit significantly more than that,” he said.
“It’s urgently required that the Ministry of Justice works with us and others to promote the benefits of being a magistrate, with a particular focus on underrepresented groups.”
Magistrates are unpaid volunteers who deal with about 95% of criminal cases alongside a legal advisor.
They must be over 18 and retire at 70, and must sit in court for at least 13 full days (or 26 half-days) a year.
Employers are legally required to give magistrates time off to serve, and training is provided on the job.
Of the magistrates in Gwent, 96% are white, and 53% are over 60. There are no magistrates under 30.
HMCTS has said that it is working with the Judicial Office and other Government departments to develop a strategy for the magistracy that will aim to improve diversity as a whole, including recruiting younger magistrates.
Since 2016, at least six magistrates’ courts have closed in Wales as part of a Government initiative to “modernise” the court system and cut down on costs.
An HMCTS spokesperson said: “With an increasing use of digital services, it makes sense to consider where and how justice is administered.
“We are also reinvesting £115m raised from the sale of underused court buildings, and making better use of technology to improve access to justice for vulnerable victims and witnesses.”