The number of magistrates in West Yorkshire has plummeted by more than a third in just three years - one of the steepest drops across the whole of England and Wales.
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 753 magistrates currently sitting in the area, compared with 1,174 three years ago.
Magistrate numbers are falling significantly in 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."
Independent charity Transform Justice has said that these two-person benches are a serious problem.
Charity director and former magistrate Penelope Gibbs said: "In these cases the bench is likely to be less diverse, and decisions not as fair.
"It's a principle of judgement by peers that magistrates should sit as three, so there can always be a majority.
"When a bench is just two magistrates, one must 'win' if there is conflict."
Her Majesty's Courts and Tribunals Service (HMCTS) has said that during the last 10 years the workload in the magistrates' court has reduced, but according to Transform Justice, the cuts have gone too far.
Mr Collins said that for magistrate numbers to remain constant over the next 10 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 North and West Yorkshire, 88% are white, and 58% are over 60. There are only two 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.
The Magistrates Association wants more money spent on raising awareness and advertising the opportunities of being a magistrate. It also wants a modernised application system, to encourage younger magistrates to apply.
"This is money that would more than be repaid in the thousands of volunteer hours that magistrates put in to keep the justice system going," Mr Collins said.
He added: "Everyone working in the justice system knows budgets are tight, but it's important that justice is done swiftly and locally."
Since 2016, at least six magistrates' courts have closed in the North East justice area as part of a Government initiative to "modernise" the court system and cut down on costs.
Between now and March 2024, HMCTS plans to cut 5,000 full-time courtroom staff and reduce the number of cases held in physical courtrooms by 2.4m per year, partly by allowing some defendants and witnesses to give evidence via video links.
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."
But Mr Collins expressed concerns that rural court closures could affect magistrate numbers.
He said: "While magistrates are willing to travel, it's important to recognise that court closures might mean people are less able to become magistrates, particularly if they have childcare or other caring responsibilities."
Law Society president Christina Blacklaws said: "Magistrates have to travel further, unpaid, for the privilege of sitting as a magistrate, and they lose the close connection to local justice in their home area that often attracts people to the role in the first place.
"This particularly affects people in rural areas, those with disabilities, and lower income families.
"Twenty years of cuts have heaped colossal pressure on the entire justice system, and those who work hard every day to ensure the rule of law is upheld."