Hundreds of Renewable Heat Incentive boiler owners have won High Court permission to challenge plans to publish their names.
On Friday, a judge granted leave to seek a judicial review of Economy Minister Simon Hamilton’s decision to reveal a list of those on the botched scheme.
Mr Justice Deeny held that a group of boiler operators have established an arguable case that the move breaches privacy and data protection laws.
He said there remains uncertainty at this stage over whether names can be lawfully disclosed.
“It may well be that the Minister is perfectly entitled to publish the identities of these recipients, but it does seem to me a matter that justifies further investigation,” he added.
The judge also confirmed an interim injunction to stop identification of more than 500 members of the Renewable Heat Association of Northern Ireland remains in place.
With a full hearing now set to take place before next month’s Assembly elections, lawyers are expected to return to court next week to establish if any companies on the list are also covered by the temporary ban.
Mr Hamilton was due to publish the names of users on Wednesday.
But lawyers launched legal action against the move, claiming it would create a media “feeding frenzy” and threaten the reputation of individuals who have done nothing wrong.
The RHI scheme set up to encourage businesses and other non-domestic users to move from using fossil fuels to renewable heating systems.
But it has been surrounded by relentless controversy since it emerged that users could legitimately earn more cash the more fuel they burned.
The flawed scheme, which could end up costing the public purse up to £490m, was a major factor behind Stormont’s collapse and snap elections.
A public inquiry to be chaired by retired appeal court judge Sir Patrick Coghlin has been announced.
Judicial review proceedings against the plans to name recipients were issued by Michael Doran, chairman of the Association.
Mr Doran, who also heads up not for profit group Action Renewables, does not have a boiler and receives no subsidies under the scheme.
But he is representing hundreds of non-domestic operators, including poultry and mushroom producers, seeking an order quashing the Minister’s plans to reveal their details.
Counsel for both Mr Doran and a boiler owner referred to as DA told the court media coverage of the so-called “cash for ash” scheme had been “sensationalist”.
Publicity has centred almost exclusively on alleged abuse of the system where money can be made through burning fuel unnecessarily, he claimed.
The barrister revealed that DA has spent around £300,000 in purchasing and installing biomass boilers for his poultry business.
He argued that those on the non-domestic scheme have a legitimate expectation that their privacy would be protected.
Publication would deflect criticism from officials and political representatives onto many individual RHI recipients who have been operating the boilers legitimately, it was claimed.
Counsel for the Department countered that public interest issues outweigh any privacy entitlements.
Pointing to the potential £490m costs over the next 20 years, he stressed the need for transparency and the “profound public interest” in understanding how the scheme was set up and run.
Mr Justice Deeny stressed that his decision to grant leave was no indication of the final outcome in the case.