More than 57,000 people are currently on police bail, with thousands waiting over six months to discover whether they will be charged, research shows.
In one case a person arrested three-and-a-half years ago remains on bail, according to data collected by the BBC.
Figures from 34 of the 44 police forces in England, Wales and Northern Ireland which responded to a Freedom of Information request show that at least 57,428 people are currently on bail, the study for BBC Radio 5 live found.
Of those, 3,172 have been waiting for more than six months for a decision on charges.
The largest number on bail was in the Metropolitan Police force's area - 12,178 - with West Yorkshire second on 3,979. Greater Manchester has the third highest number, 3,854.
The Met has the highest number on bail for more than six months, 910, with West Yorkshire second, 859, and Lancashire third, 187.
The figures include one case of an individual who has not been told whether or not they will be charged despite having been arrested and bailed by the Metropolitan Police three years and seven months ago, the BBC found.
The Law Society told 5 live it wanted a review of police bail practices and said there should be a statutory time limit.
Richard Atkinson, chairman of its criminal law committee, said: "I would call for a 28-day statutory maximum period for police bail. But it could be extended by applying to a magistrate.
"There, police would have to explain what stage they were at in their investigation and why a further 28-day extension of bail was necessary."
Steven, a former teaching assistant from Newcastle, told the BBC: "After I was arrested, I was on bail for five months before I was told that no further action would be taken against me."
He was arrested in connection with an allegation of sexual assault which turned out to be false.
He said being on police bail and waiting for a decision from the Crown Prosecution Service (CPS) can have a big impact on the lives of those arrested.
"I was suspended from my job and I was scared to leave the house because I was paranoid that people knew I was a police suspect," he said.
"I became severely depressed and contemplated suicide. The uncertainty of not knowing when my ordeal would be over was awful."
Steve White, vice chairman of the Police Federation, told 5 live: "Resources are always going to have an impact in terms of how quickly we can get stuff done. We are still in the process of dealing with the cuts we are having to face."
He said cuts to the CPS were having a knock-on effect and added: "The police service is being asked to do more with less and there comes a point where you can't do any more or do it any quicker."
A Home Office spokesman told 5 live: "We continue to keep police bail provisions under review to ensure they strike the right balance between protecting an individual's right to civil liberty and allowing police to carry out thorough criminal investigations."
The Metropolitan Police told 5 live about the longest bail case that a man, now aged 45, was arrested on October 2 2009 on suspicion of fraud.
He remains bailed to return to a central London police station pending further inquiries. It has been a very lengthy and complex investigation.
Nottinghamshire Police Chief Constable Chris Eyre, lead on criminal justice for the Association of Chief Police Officers, said: "Police bail is an essential tool in securing justice.
"It allows investigators to ensure every possible avenue is explored, while those arrested need not remain in custody.
"Each and every investigation follows a different path, and detectives will go where the evidence leads them.
"The huge complexity of some investigations in the 'information age' can mean this takes time.
"Hi-tech crime investigations, computer forensics, CCTV, telephony, using interpreters or gathering evidence across borders and jurisdictions can all take time and painstaking analysis.
"We would all agree that criminal cases should be concluded as swiftly, justly and transparently as possible.
"This is important both for victims, and in preserving public confidence in the criminal justice system as a whole. But officers must have the time needed to deal with complex investigations appropriately and thoroughly."