The case concerns the deal underpinning the area's regeneration.
The harbour ultimately owns the land in the area and it is leased to Titanic Quarter Ltd (TQL) under a "master agreement."
On Wednesday, TQL's barrister said the agreement is not written in the "language of veto", but aimed at finding consensus.
TQL has previously said it was having difficulties advancing new projects with Belfast Harbour under the master agreement.
It described these difficulties as "the most significant impediment to the group's future progress".
A temporary exhibition centre was opened at Titanic Quarter last year, but a number of other projects have not been started despite having planning permission.
Those include two film studios which received permission in August 2014.
TQL and the harbour are asking a judge to rule on the correct interpretation of the master agreement.
Under its terms, TQL can bring forward development proposals for agreement with the harbour.
A barrister for the harbour, said his client's only obligation was to consider such proposals in "good faith", but could choose to reject them without explaining why.
He said TQL was attempting to "magic" a limited agreement into "an overarching obligation."
Lawyers for TQL said the firm has never claimed there was a "compulsion" for the harbour to agree.
However, he said that consultation on particular developments should happen with "a view to agreement".
It is understood that TQL also believes the harbour has acted in bad faith by rejecting some projects but the current proceedings do not consider that issue.
The harbour reject the claim of bad faith.
The case continues.
Belfast Harbour has a "veto" over any development in the city's Titanic Quarter, the High Court has been told.