NSW authorities are likely to face an uphill battle trying to implement new "very unenforceable" rules that make it compulsory to report positive rapid antigen test results for COVID-19, a law academic says.
From Wednesday, NSW residents who fail to report positive RAT results will face a $1000 fine as the state transitions to a testing program based on the at-home testing kits, rather than PCR tests.
Under the new regime, unveiled by Premier Dominic Perrottet on Wednesday morning, it will be mandatory for residents aged over 16 to log any positive RATs they have taken this year via the ServiceNSW app or website.
Chris Rudge, an expert in health law and medical regulation from the University of Sydney, labelled the new system as "very unenforceable".
"I can't think of many legal instruments that are more unenforceable than this," Dr Rudge told AAP.
"It inevitably will be either very selective or very patchy, there's no uniformity or equity of oversight here."
He said two groups in particular are likely to be in the sights of authorities - people hospitalised with COVID-19, and those living in a "group setting".
That is because COVID-19 positive patients in hospital could easily be questioned about whether they had reported a positive RAT test, while those in share houses or living with family could be "dobbed in" by housemates.
Adding to problems for authorities, he said, were evidentiary stumbling blocks that could hamper prosecutions for alleged flouting of the rules.
Dr Rudge pointed to police having to unearth a positive COVID-19 RAT result, or a record or photo of one, to prove a breach of the rules.
"It's very hard to prove if there's no positive test available," he said.
He described the mandatory RAT reporting regime as largely about "self regulation", despite the threat of financial penalties for non-compliance.
"The problem with self-regulation is it's pretty hard to enforce unless there is some chance intervention or a dob in, or something additional to the self-regulation," he said.
The stricter rules come as NSW set a record for its deadliest day of the pandemic, with 21 people dead and 34,759 new COVID-19 cases reported.
Some 2242 people are in hospital with the virus across the state, 175 of them in intensive care.