STORMONT departments have unique legal power to take decisions in the absence of ministers, the Court of Appeal has heard.
Senior judges were told parliament anticipated periods of hiatus where Northern Ireland would have to be run without a functioning Executive.
The Department for Infrastructure is seeking to overturn a ruling that a permanent secretary unlawfully approved a £240m waste incinerator on the outskirts of north Belfast.
In May the High Court held that the senior official did not have the legal authority to grant permission for the waste disposal facility at Hightown Quarry in Mallusk.
Appealing that verdict, the department's lawyer Tony McGleenan said since the devolved administration collapsed more than a year ago governance "has continued to function because of the unique constitutional arrangements that operate in this jurisdiction, which allow for powers to be discharged by departments".
He argued that the legal right stemmed from the Northern Ireland Act - with no equivalent provisions for other parts of the UK.
Likening the departments at Stormont to corporate bodies, Mr McGleenan stressed that civil servants were not making decisions as individual employees.
"We have departments discharging their statutory functions, there's an important conceptual difference. These are decisions of departments."
A 25-day period following the March 2017 assembly elections triggered by Martin McGuinness's resignation as Deputy First Minister was cited as evidence of duties continuing in the absence of ministers.
The court was told social security decisions are taken on a daily basis to provide benefits for the most vulnerable and needy.
Mr McGleenan also insisted that departmental action has been restrained over the past 16 months, only taking significant decisions when there has been pressing public interest.
However, David Scoffield QC, representing Colin Buick of community group NoArc21 who took the initial judicial review proceedings, argued that legislation has made clear a department's functions will "at all times" be subject to the direction and control of a minister.
Decision making without such control is democratically unaccountable and invalid, he claimed.
The appeal continues.
