Ben Derbyshire, a director at HTA, said: "This was a trial of preliminary issues clarifying the way forward. We are taking advice on the next steps."
It is thought HTA will now look to recover a reasonable sum for work done. It will not be able to pursue damages under breach of contract.
The architect's dismissal from the project in June 1999 came after HTA threatened to resign, claiming that its design had been diluted.
In a four-page letter dated 25 June last year, the developer listed four grounds for dismissal, covering production of information, design and practice organisation.
GMV project director Ross Hammond praised the decision. He said: "GMV has always considered that the termination of HTA's involvement was entirely justified and its claim has been refuted repeatedly both in principle and in substance."