Doctors have moved to shut down an inquest into the deaths of four cancer patients who were underdosed with chemotherapy in what a surviving victim has labelled "heartless legal tactics".
Since mid-2016, South Australia Deputy Coroner Anthony Schapel has been looking into the deaths of leukaemia patients Christopher McRae, Bronte Higham, Carol Bairnsfather and Johanna Pinxteren.
All four were among 10 patients who were underdosed during their chemotherapy treatment at the Royal Adelaide Hospital or Flinders Medical Centre between July 2014 and January 2015.
On Thursday, Daryl Trim QC, representing a number of doctors, said the deaths of Ms Pinxteren and Mr McRae were not reportable to the coroner because they could not be directly linked to the underdosage.
"There is no evidence to support that the deaths of Ms Pinxteren and Mr McRae were reportable deaths," he told the court.
"One cannot say whether those persons would have experienced a shorter survival duration."
The Coroner's Act outlines a specific set of circumstances which qualify a death as reportable, but Mr Trim argued the two deaths did not fit into any of the categories.
He said the other two deaths were reportable, but should not be investigated because the coroner "cannot disjoin the inquest".
A representative for the Crown said the Director of Public Prosecutions had not yet formed a position on the matter, while counsel assisting the coroner indicated she would oppose the submission.
Andrew Knox, one of the patients underdosed, branded the legal challenge "heartless legal tactics" and said the inquest had uncovered the "worst of the worst of medical accountability".
"We're not dealing with the inescapable fact that, regardless of the medical opinion one way or the other, we were denied our best chance of survival and prolonged life," he told reporters outside court.
"If the submissions are accepted, even in part, it means that we won't get to the whole bottom of the behaviour and it will not stop."
The inquest was due to hear closing submissions on Thursday, before Mr Trim flagged he would launch the legal argument.
The Crown is expected to state its position early next week, but it is not known when the coroner will make a ruling.
"I would think we're some weeks away and then if it goes across the road to the Supreme Court we're months away and maybe more," Mr Knox said.
"It just prolongs the pain."