STORMONT'S introduction of reduced payments for the Renewable Heat Incentive scheme was "nowhere near" any abuse of power, the High Court has heard.
A judge was told primary legislation provided legal authority for the move.
A lawyer representing the Department of the Economy also argued that even if the cost-cutting regulations are quashed, boiler owners could not revert to the higher rates.
With payment mechanisms under the old scheme now repealed, other potential remedies would have to be explored.
Judgment was reserved today in an action mounted by more than 500 members of the Renewable Heat Association NI Ltd.
They are seeking to judicially review the department for cutting payments assured under the original 2012 regulations.
According to their case it was an unlawful step taken against operators with a cast iron 20-year guaranteed rate of return on their investments.
Tony McGleenan QC, for the department, insisted the action was taken for legitimate reasons to protect the public purse, correct flaws in the scheme and comply with EU rules on state aid.
"That's nowhere near an abuse of power," he said.
Mr McGleenan also contended that the 2011 Energy Act provided the power to change the regulations.
Gerald Simpson QC, for the association, countered by setting out the contents of government documents and correspondence he said contained "clear, unequivocal representations" that the original rate would be paid for 20 years.
Referring to any suspicions of potential abuse of payment arrangements, he challenged the department to produce details so anyone involved can be removed from the scheme.
"There's no serious evidence of misuse; if there was something could have been done about it."
As the five-day hearing came to an close, Mr Justice Colton said he will "try and give my judgment as soon as I can".
