The castle and several inflatable Zorb balls at Hillcrest Primary School in Devonport were lifted into the air by a wind gust on December 16, 2021.
Preparations for an inquest into the deaths of Addison Stewart, Zane Mellor, Jye Sheehan, Jalailah Jayne-Maree Jones, Peter Dodt and Chace Harrison were put on hold in February.
The inquest was told WorkSafe Tasmania refused to hand over documents to the coroner because doing so could prejudice the regulator's investigation and potential prosecutions.
Legal action launched by WorkSafe Tasmania aimed at preventing the coroner from obtaining the documents was heard in the Supreme Court of Tasmania on Monday.
The court was told the documents include an engineer's report, and statements of three TaZorb employees and two department of education staff.
WorkSafe Tasmania's lawyer, Michael O'Farrell SC, said releasing the documents could compromise potential prosecutions and further investigations.
He indicated the Director of Public Prosecutions (DPP) had a WorkSafe Tasmania report and was still considering whether to prosecute.
"The matter remains under investigation and that is an important element of our claim in this case," O'Farrell said.
He said granting the coroner access to the documents could lead to a scenario where the DPP could say there was insufficient permissible evidence to be able to prosecute.
Under Tasmania's workplace safety laws, prosecutions can only be brought within two years of an incident, meaning there is a December deadline.
Leigh Mackey, lawyer representing the coroner, said it was "unclear" how future investigations could be impacted by the disclosure of the documents.
She said the investigation had finished and witnesses had already given statements.
Mackey said many jurisdictions were interested in the outcome of an inquest and one should be held quickly to ensure recommendations could be made to reduce future risks.
O'Farrell said he didn't denigrate the important functions of the coroner but the likelihood of an event like the tragedy happening in the short-to-medium term was very small.
Justice Gregory Geason will deliver his decision at a later date.
The one-year Hillcrest anniversary was marked last year by a ceremony in Devonport, while there are plans for a permanent memorial.
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