The Crown Prosecution Service needs an urgent injection of cash to pay for the “explosion” in its digital disclosure workload, the union representing its lawyers has said.

A “Manifesto for Justice” has been launched by the FDA, formerly the First Division Association, in the wake of a row over how police and the CPS handle rape and sexual assault complaints.

The document also calls for improved resources for the CPS, a ban on further cuts to legal aid and “competitive” pay to recruit and retain prosecutors.

The four key demands are supported by the legal profession’s main membership bodies – the Law Society, representing solicitors in England and Wales, and the Bar Council, which represents barristers.

The FDA published its programme on Wednesday, highlighting the growing pressure on lawyers who have to wade through vast volumes of potential evidence downloaded from mobile phones, laptops, CCTV cameras and computers.

“Twenty years ago, schedules of evidence in criminal cases were fairly short and straightforward,” the FDA document said. “If digital evidence existed at all, it might amount to a couple of text messages. However, there has been an explosion in digital media.

“Many people now carry two or three digital devices that not only send and receive text messages and emails, but also store messages from a variety of social media apps including Facebook, Twitter, Snapchat and WhatsApp. Police also carry body cameras, which can generate hundreds of hours of footage.

“This is an enormous amount of information to look at. Just 1GB of data equates to 20,000 pieces of paper. It’s no wonder that in a recent FDA survey of prosecutors, 95.3% of respondents felt that disclosure issues have become more time consuming since 2010.

“Yet while disclosure [the duty to share evidence with the defence] has become more time consuming since 2010, the budget of the CPS has fallen by 25% in the same period. As a result, 95.7% of prosecutors surveyed by the FDA now think the CPS does not have enough lawyers to deal with disclosure issues.”

Fiona Eadie, the FDA’s president and a former prosecutor herself, said: “This investment in the future is essential to stop a brain drain to other areas of law and ensure a properly functioning criminal justice system.”

Chronic overwork is common, according to the FDA’s 2018 working hours survey, which found that 92% of its CPS members regularly worked more than their contracted hours and 79% had worked while on sick leave.

Christina Blacklaws, the president of the Law Society, warned that years of underinvestment had left the criminal justice system “crumbling”.

Richard Atkins QC, who chairs the Bar Council, said: “The failure to increase rates of pay for publicly-funded lawyers, both prosecution and defence, is nothing short of a scandal.”