Hundreds of people with mental health problems are dying while detained in hospital but their deaths are not being fully investigated.
Legal experts and campaigners claim coroners are failing to investigate thoroughly many of these deaths because of a legal loophole, with the result that suspected failures in care and even abuse are going undetected.
Coroners have complete freedom to determine the extent to which the death of a mental health patient will be investigated, unlike deaths in prison or police custody where they are legally compelled to investigate fully in the presence of a jury.
In many cases they are refusing to hold jury inquests – widely seen as a broader and more exacting form of inquiry.
Figures obtained by The Independent on Sunday show that 340 people died in psychiatric hospitals while under section last year – nearly one a day – although the Mental Health Care Commission believes some deaths in psychiatric care are not being reported.
As a result, grieving families are left to battle an "archaic system", often for years, just to find out how their relatives died.
Critics claim it is evidence of the discrimination suffered by mentally ill people and are demanding urgent changes to the law. "We are talking about the ultimate injustice; people go into hospital for a mental illness and are coming out dead. We need to send out a clear message that whatever happened to the individual behind closed doors is worthy of a thorough investigation," says Paul Farmer, chief executive ofthe mental health charity Mind
Coroners failing to investigate the deaths of psychiatric patients to the satisfaction of the families now face a High Court legal challenge.
Sandra Allen, a pianist and manic depressive, died of a heart attack in a north London psychiatric hospital in 2006.
A coroner ruled she died of natural causes which were unavoidable, but her children are challenging the coroner's verdict because they believe their mother's death could have been avoided with better care.
Mrs Allen, 61, died from a heart attack after choking on a sandwich she had been left to eat unattended: she had no dentures and a long history of choking. Staff failed to clear her airways and were unable to operate an oxygen canister. She was still choking when the ambulance arrived. It had waited for several minutes outside the unit because the security guard was asleep.
Her family argue the coroner was wrong to reject their request for a broader inquiry as much of the psychiatric and physical care she received while under section was unacceptable and they believe it contributed to her untimely death.
Devastated by the coroner's refusal to hear evidence from expert witnesses, they say they will fight "as long as it takes".
Solicitor Emma Norton, who acts for the family, said: "This case highlights the difficulties often faced by families in ensuring there are thorough inquiries into the deaths of patients in psychiatric institutions.
"Unlike prisoners, the families of dead patients are not automatically entitled to an inquest with a jury. It can be an uphill battle to get the coroner to consider the wider issues relevant to the death. There is a lot of inconsistency in these decisions and it depends on the coroner."
Critics argue patients who have been locked up and compelled to take treatment they did not want deserve an equal standard of justice when they die.
"This situation is indicative of how few rights mental health patients have. They have done nothing wrong; their only crime is to suffer from an illness, yet they have fewer rights than criminals," says Jane Harris, from the mental health charity Rethink.
"How many more people have to die without proper investigations? We are talking about hundreds of deaths."
Campaigners hoped the Government's proposed Coroners Bill might remedy some of the failings, but it was not mentioned in the Queen's Speech.
A spokeswoman for the Ministry of Justice said: "The Bill proposes that a coroner will investigate a death if they suspect the deceased died while detained, irrespective of the nature of the death or the type of detention."
But the co-director of Inquest, Helen Shaw, said: "We cannot take it for granted the Coroners Bill will happen just because the Government says it will. We need to crank up the heat and campaigning so detained patients are treated in the same way as any person detained by the state."
Andrew Lansley, shadow Secretary of State for Health, said: "There is a pressing need for this Bill. The Government promised one and they have had plenty of time to do so, but they have dithered and delayed."
'Whenever we visited her on the ward she would be covered in bruises'
Steven Allen, 23, a trainee lawyer, is the second of Sandra Allen's five children. Here he describes the family's determination to get justice for their mother.
"My mum died in hospital while held under section 3 of the Mental Health Act. She was 61 years old. Her life was a long battle with the mental health system and now she's dead we have to keep battling for her.
"She'd been in and out of hospitals since her 20s but as her physical health got worse we fought hard to get her looked after properly; we never won the fight. Whenever we visited her on the ward she would be covered in bruises and we would leave feeling terrified for her.
"We desperately wanted her moved to the elderly ward but were told she was too young and they wanted to 'keep muddling through'. I'm sure the staff on the elderly ward would have been better qualified to manage the heart attack.
"We believe she died needlessly. Why hadn't her heart disease been picked up? Why couldn't the staff work a simple oxygen canister? These are the questions we wanted the coroner to answer but he let us down badly; he dismissed my mum's life as unimportant.
"We know this could take years but we want her struggles acknowledged and justice, not just for her, but for every other family in this situation."