"Persons should not be placed in a position where they can be led into unwise decisions," coroner David O'Connell said in his findings handed down on Wednesday.
The Coroners Court in Brisbane in February held an inquest into the May 2023 death of a man aged in his 80s referred to by the pseudonym ABC.
Mr O'Connell heard ABC kept a voluntary assisted dying (VAD) substance in his home after it was no longer required.
In his findings, Mr O'Connell said he was not judging the merits of VAD but it had led to a "tragedy" within 107 days of being legalised.
He found the current laws had "overwhelmingly favoured" giving terminally ill patients' autonomy to the point of letting people take personal possession of the most dangerous drugs legally manufactured in Queensland.
"The VAD law has (the substance) provided to persons with no medical training, no regulatory oversight, and in a period of great personal and emotional turmoil," he said.
ABC's name and those of his family members along with many other details surrounding his death cannot be published for legal reasons.
The substance involved in ABC's death was obtained legally after Queensland allowed VAD in January 2023.
Under that law, a person can self-administer a VAD substance in a private location but they must nominate a person who will be legally required to return any unused or leftover portion within 14 days.
The man did not return the VAD substance to a hospital due to being unable to leave his home and there was no arrangement made for a health professional to collect it.
ABC's adult daughter told the inquest she held his hand and shook him after returning from running errands to find the house locked up with the blinds drawn.
"I thought he was asleep in the chair. I put my arms around him. He was cold," the woman said.
Becoming tearful and with her voice breaking with emotion at times, the woman said she found an empty box in the kitchen and "knew immediately it was the VAD".
Mr O'Connell found there was no breach of the law by health authorities despite the VAD substance in ABC's home being overdue for return.
"It is clear that the system and its purportedly rigorous 'check and balances', had several operational flaws. ... it was, in my respectful opinion, not a well-considered law," Mr O'Connell said.
He recommended the Queensland government implement an earlier draft of VAD laws that required oversight by a medical professional at all times.
Queensland Health Minister Shannon Fentiman said the government would consider the coroner's recommendations and had "already done some work in that respect".
"Following that case, we are working on a review of that legislation coming up to three years that will start next year, and that will obviously be one of the things that we look at," she told reporters.
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