The wait time before people accused of the most serious crimes in Scotland will appear at a High Court trial is set to almost triple by 2028.

The Scottish Courts and Tribunals Service (SCTS) forecasts that the average wait after pleading diet – when the accused first appears at a hearing – will increase from 50 weeks to 135 weeks.

It comes as the number of High Court indictments served by the Crown Office is expected to exceed 2,700 this year, compared to 935 in 2023/24.

SCTS said much of the case load is due to increased rates of prosecution of serious sexual offences, domestic abuse and organised crime.

SCTS chief executive Malcolm Graham told BBC Scotland News: "Around 70% of the cases that come to trial in the High Court are serious sexual offences and that has increased hugely over a very small number of years.

"In some regards it's a huge success that society and the agencies involved are able to tackle the scourge that our society faces.

"But the system needs to be prepared to deal with that"

Graham says the potential impact of such long trial delays on everyone involved - victims, witnesses and those accused - is concerning.

"It doesn't serve people's needs if there's uncertainty," he added.

"If there's a length of time between when a crime is committed and when a case comes to trial, or when it's concluded in some other way, the longer that is, then the more impact that has on victims.

"There is some evidence that having an extended period [makes it] far more likely for victims and witnesses not to be able to fully engage in the process for all sorts of different reasons."

The High Court currently sits at 10 venues around Scotland, but it will expand to four more Sheriff Courts next year at Airdrie, Dunfermline, Edinburgh and Glasgow, in order to increase capacity.

This will allow up 26 trials to sit each day, compared to 16 at the start of the decade.

Graham said the focus of SCTS continued to be on trying to reduce the length of time people wait for the outcome of a case, but they need around £62m over five years to update court processes and reform criminal case management.

He said: "We haven't got joined up data systems. We haven't got digital systems that are shared across the organisations from the police to the Crown to the courts to criminal justice social workers.

"We're able to put in place much more efficient ways of transferring information that rely on modern technology and not on paper-based systems.

"I don't think it's a stretch to say that the fundamental processes that underpin how criminal courts are run, still look like they might have looked like around about 100 years ago."

Calls for modernisation are being backed across the legal profession.

Tony Lenehan KC, vice dean of the Faculty of Advocates, says the way he works has changed significantly.

"I have made the transition from carting dozens of kilos or hundreds of kilos of papers to cases into court for big cases to just carrying my laptop," he said.

"The more we move towards everything being accessible in a digital way, it streamlines everything.

"That's going to have benefits right across the system."

Lenehan also said that timely access to a trial is a fundamental right of those accused of crimes.

He said backlogs were affecting the more than 2,000 people on remand in Scotland's prisons - who are awaiting trial and have not yet been convicted.

He added: "There will be people who are spending time on remand just about equivalent to the sentence that they're going to get if they're convicted - and these are people who are presumed to be innocent.

"People should only be deprived of their liberty where it's absolutely essential and for as short a period as possible."

The Scottish Prison Service says the size and complexity of the current prison population was "unsustainable".

It said it posed a significant risk to the safety of inmates and staff and limits the ability to deliver effective rehabilitation.

A spokesperson said: "We need a safe and sustainable prison population, including those on remand, to ensure we can fully support those in our care, reduce the risk of reoffending, and help build the safer communities we all want to see."

Victim Support Scotland said an increase in high court trials was a "positive step" towards tackling court backlogs.

Chief executive Debbie Adams said: "One delay has a knock-on effect for the entire justice process, so anything that can be done to help reduce the time victims spend waiting is welcome."

The Scottish government said it was continuing to work closely with justice partners, including the SCTS, on reform measures and was "providing targeted investment to ensure victims and witnesses experience a more efficient, trauma-informed justice system".

A spokesperson added: "We recognise the growing volume of serious cases and continue to invest in court capacity.

"We will invest £11.6bn across the justice system in 2026-27 to 2028-29 as we continue to support frontline services, build safe communities, reduce crime and re-offending and support victims and witnesses."

They added that reforms were required to "respond to society's changing needs, remove duplication and ensure there are modern user-centred digital services".

Examples of this include expanding digital evidence sharing capability and enabling police and expert witnesses to give their evidence remotely.