Campaigners are calling for an end to currently active indeterminate sentences, which thousands of offenders are still serving despite the fact they were abolished in 2012.
Imprisonment for Public Protection (IPP) sentences were introduced in 2005.
However they were abolished in 2012, after being described as the "single greatest stain" on the criminal justice system by former Supreme Court justice, Lord Brown.
John Cavanagh was 26 years old when he was given an IPP sentence with a five-year minimum term for armed robbery.
He was released after serving five years, but has been recalled twice for breaching his IPP licence, which lasts 99 years.
It means he's served a decade over his original tariff.
His mother, Marie Cavanagh, was forced to face another Christmas without her son.
Ms Cavanagh told Sky News: "As far as I'm concerned, John isn't dangerous, he's traumatised and there's no support
"He phoned me up one Christmas and he said to me: 'Mum, I can't do it anymore. I'm on a hunger strike.'
"We're all crying, John's crying down the phone on many occasions."
Ms Cavanagh says she lives in "fear that I'm going to get the phone call to say he's died".
IPP sentences were intended to be for criminals considered to be a high risk - a total of 8,711 were issued.
But, there was no retrospective change for those who had already been sentenced under the legislation when it was scrapped in 2012.
Government figures show that 1,722 prisoners on IPP sentences are still incarcerated, with 96% held beyond their minimum term.
A total of 1,332 have been recalled.
The mental health crisis among IPP prisoners is rife, with 70 suicides recorded between 2005 and March 2021, according to the United Group for Reform of IPP (UNGRIPP).
Tommy Nicol took his own life in 2015, after he was given an IPP sentence with a minimum term of four years in 2009.
His sister, Donna Mooney told Sky News: "I had contact with my brother, but it was quite sporadic and he definitely pulled back a lot" after his mental health began to deteriorate.
"My brother wouldn't be dead today if he hadn't been given an IPP sentence. I have absolutely no doubt in my mind about that.
"He said it himself."
She's now campaigning for change with UNGRIPP.
Ms Mooney said: "The government has spent ten years to trying and fix this, and they've tried, but we still have a massive problem.
"The only way to fix this is through resentencing, and if they don't resentence, there needs to be political change around the licence conditions."
Karl Maroni also saw his mental health deteriorate while serving his IPP sentence.
His tariff was three-and-a-half years for robbery with an imitation firearm, but he's served 16 years so far.
His sister, Tasha Maroni said he became "very unwell" which saw him transferred to a secure forensic mental health hospital four years ago.
Ms Maroni told Sky News: "My brother has been in prison with some high-profile individuals who have done worse crimes, and he's seen them out of prison for worse crimes with a shorter sentence.
"Enough is enough."
Forensic psychiatrist Dr Dinesh Maganty told Sky News: "IPP sentences have led to a sense of hopelessness, and have been traumatic and in many instances toxic to the mental health of prisoners.
"This has resulted in serious self-harm and deaths."
He added that mental illness shouldn't be treated "as a risk" when decisions are made on parole or recall.
A Ministry of Justice spokesperson said: "The number of IPP prisoners has fallen by two-thirds since 2012.
"We are helping those still in custody progress towards release, but as a judge deemed them to be a high risk to the public, the independent Parole Board must decide if they are safe to leave prison."
Anyone feeling emotionally distressed or suicidal can call Samaritans for help on 116 123 or email firstname.lastname@example.org in the UK. In the US, call the Samaritans branch in your area or 1 (800) 273-TALK.