The family of the late Zachary Gravatt say they have been denied justice after the Health and Disability Commissioner's office decided against a formal inquiry into his medical care.

Mr Gravatt died aged 22 in Auckland City Hospital in July 2009 from organ failure caused by infection with meningococcal C bacteria.

His father, Lance Gravatt, had hoped to go to the Human Rights Review Tribunal to make a damages claim against the Auckland District Health Board for out-of-pocket expenses such as the thousands of dollars spent on obtaining expert medical opinions.

But he said the only payment his son's estate had received from the wider health system was a $5700 funeral grant from the Accident Compensation Corporation, despite evidence of substandard care and the possibility that his son might have been saved by earlier recognition and treatment of his illness.

Dr Gravatt said it had been exhausting and difficult to obtain the grant, which covered less than half the cost of the funeral.

"While none of this is about money and no amount of money can replace Zachary, the ACC grant for fatal treatment injury is an absolute insult.

"People in New Zealand are awarded $10,000 by the Employment Relations Authority for a boss that swore at them. Victims of fatal accidents are awarded hundreds of thousands [after prosecutions] by OSH. But if you die as a result of a treatment injury then you had better dig in for a very difficult, long fight for $5700."

In a letter to Dr Gravatt, Deputy Commissioner Theo Baker explains the decision against an investigation.

"I note the events leading up to Zachary's death, and the care he received at Auckland City Hospital, have already been substantially investigated by the DHB and the coroner," she says. "Areas where the care provided could have been better have been identified, and recommendations for improvement made, for the benefit of future service users."

Her decision may have ended any chance of Dr Gravatt, as administrator of his son's estate, going to the tribunal. An "aggrieved party" - a patient or the executor/administrator of an estate - can take a health provider to the tribunal under the Health and Disability Commissioner Act but only in tightly prescribed circumstances.

These are that the commissioner has formally investigated and found a breach of the code of patients' rights. Further conditions are that either the commissioner has decided not to refer the case to his office's independent prosecutor or the prosecutor has declined or failed to take the case to the tribunal.

Auckland University health law expert Associate Professor Joanna Manning said access to the tribunal was too restricted. A process to review a commissioner's decision not to investigate should be created, complainants should be permitted to go to the tribunal when no breach was found, and providers should have the right to have a review of commissioner decisions.

Dr Gravatt said his bid to go to the tribunal had been stymied by the health board's pointing out to the tribunal that he lacked the right to take a case because of the absence of a commissioner investigation.

He noted the findings of an Accident Compensation Corporation reviewer, based on the reports of medical experts, that delays in treating his son in hospital most likely caused his death.

The coroner said the fault lay with the health system, not individual staff.