The South Australian Opposition says incidents in the South Australian health system are the subject of secret inquiries outside the reach of the coroner's court.

SA Health Authorities are scrambling to correct mistakes that led to botched chemotherapy processes at the Royal Adelaide Hospital (RAH) and Flinders Hospital.

The Government's own reports say “the level of investigation required wasn't undertaken”, and that the Royal Adelaide Hospital “did not conduct a root cause analysis investigation”.

Root cause analyses (RCAs) were first applied in the nineteen-fifties, when NASA was investigating failures with rockets.

By now they are commonplace, and are specifically outlined in SA’s Health Act for when authorities need to get to the bottom of complex incidents.

But Opposition health spokesperson Stephen Wade says RCAs are secret by law, so not even the coroner is allowed to know their recommendations.

“To think that a court of the state which has a particular responsibility to protect South Australians from the potential for a repeat of a death is not able to get all of the information it might need to do its job I think is very concerning,” Mr Wade told ABC reporters.

Coroner Mark Johns says that the protections around RCAs mean health professionals are better protected than police informers.

“I can't understand why it's necessary to obtain a frank account of something, to offer secrecy,” Mr Johns told the ABC.

“There is no similar protection in that situation for a police informer.

“It is an accurate reflection of the law of the state and it is a bother to me because it's impossible in such a situation to be able to test what a witness is saying before the court with what they've said in this previous secret environment.”

Mr Johns said potential coronial cases at private hospitals are going un-notified because they are dealt with through the RCA process.

SA Health Department spokesperson Di Lawrence told reporters that the public system runs differently, and sometimes secrecy is required.

“The reason for [the secrecy] is to promote a positive safety culture so people can speak openly and not fear being crucified or criticised ... in a coroner's court,” Ms Lawrence said.

“And currently because it is protected we have a culture where people ring us up and talk to us very often about things that haven't gone as they should so it's actually working well.”

But that may not be enough for Mr Knox.

“For a coroner to be barred from delving into the senior medical fraternity is beyond explanation,” he said.