Victor Massey (54), of Palmerston Street, Westwood, died on 7th August 2006 just hours after a disturbance in a hospital bathroom when police used CS gas to restrain him.
He was being treated in hospital for an abdominal complaint and before the incident his family were told he was making progress and it was hoped he would be released that week.
The CPS decision not to prosecute the officers was based on the findings of an Independent Police Complaints Commission (IPCC) investigation.
Said a CPS spokesman: "Following a detailed and wide-ranging IPCC investigation, the case was considered with equal thoroughness by the CPS Special Crime Division.
"We looked at a range of issues, including manslaughter. However, in order to prosecute manslaughter, evidence is needed to establish to the criminal standard a causative link between the conduct of those under investigation and Mr Massey's death.
"Three medical experts advised on this issue but none could make this causative link. Consequently, there was insufficient evidence for a realistic prospect of conviction.
"We extend our sympathy to Mrs Massey and her wider family at this time and as in all such cases, we have provided Mrs Massey with a detailed explanation about the whole of our decision. She has also been offered a further meeting with the reviewing lawyer."
Because of the investigation into Mr Massey's death all evidence had been impounded, but his devastated family now hope the CPS decision will finally provide them with some answers.
Said the family's solicitor Paul Balen: "The family feels it is time someone provided them with an explanation of what happened that night.
"It has been a long time since he died. Hopefully this decision will mean that the information is released to us."
Mr Balen said the CPS decision was just one cog in an on-going investigation and eventually someone would have to be held accountable as there were 'real questions in the use of CS gas in a confined space'.
"No doubt there will be civil claims at the end of the day but at the time we do not have the necessary information," he told Chad.
An IPCC spokesman said the independent investigation would now be concluded and submitted to the coroner for the inquest into the death of Mr Massey.
Recommendations will also be made to the force concerning 'any potential misconduct issues and lessons to be learned from the incident'.
At the time of the incident Mr Massey was described as a 'quiet and gentle man' and a 'hardworking, devoted husband, father and grandfather who would not even harm a spider'.
