Counsel for a residents group opposed to a new 34,000-seat arena being built in west Belfast also claimed the level of uncertainty around dealing with future events should render the contract void.
A judge was told that a “hulking mass” would still overshadow homes in the area even if the venue was not in use.
In July last year she gave the green light for a new £110m stadium at the venue in Andersonstown.
But some of those living in the surrounding area object to the proposals due to concerns about the height of the arena, traffic, parking and potential disturbance from concert events.
The Mooreland and Owenvarragh Residents Association (MORA) is seeking a judicial review into the lawfulness of the minister’s decision.
Lawyers for the group have already raised constitutional issues, claiming Mrs Mallon should have obtained consent from her Stormont Executive colleagues.
On day two of the case attention turned to the terms of a Planning Agreement negotiated with Ulster GAA as part of the process.
It includes a clause relating to the appointment of a stadium manager, travel plan coordinator, event safety manager, event management group and traffic management contractors.
Ronan Lavery QC, for MORA, claimed some issues would normally be dealt with in the main application for planning permission.
“What is happening here is that a substantive decision hasn’t been made on the planning application, the whole process has been usurped by the planning agreement,” he contended.
Counsel alleged that members of the public were being excluded by the private agreement.
“It’s void for uncertainty,” he continued.
“Yes, there’s a whole tool kit, there’s an event management plan, but it doesn’t say what will happen when a 34,000-seater event takes place.
“It describes it as flexibility, we say that is uncertainty.”
Questioning the assessment of cumulative traffic in the area, Mr Lavery also suggested the availability of park and ride facilities could create issues for the stadium being used to host events.
In such circumstances, he submitted: “We are still left with this hulking mass overlooking our gardens, a big white elephant of a structure which can’t be used.”
Referring to the Stormont Executive’s commitment to redevelop Northern Ireland’s three main football, rugby and GAA stadiums, Mr Lavery said: “It seems there is a determination to get this project over the line because it was promised.”
The case continues.