Can an arbitral tribunal determine Quantum Merit claims?

Subject to an appropriate arbitration clause, yes.
- O'Connor v Leaw Pty Ltd formerly known as Mac-Corp Pty Ltd ¹⁾
- The clause in that dispute read as follows
  - If any dispute or difference concerning this Agreement shall arise between the Proprietor, or the Architect on his behalf, and the Builder then either party may give to the other notice in writing thereof and at the expiration of one week unless it shall have been otherwise settled such dispute or difference shall be and is hereby submitted to the arbitration of a person to be agreed between the parties or failing agreement within three weeks after either party has given to the other a written request to concur in the appointment of an Arbitrator then at the arbitration of two Arbitrators one of whom shall be the nominee of the President of the Chapter or Area Committee of the Royal Australian Institute of Architects in the State or Territory in which the Works are situated and the other of whom shall be the nominee of the President of the Master Builders' Association in the State, Territory or place in which the Works are situated and if the Arbitrators shall fail to agree then to an Umpire to be appointed by them.
  - Any Award made in any arbitration proceedings as aforesaid shall be final and binding on both Builder and Proprietor and neither party shall be entitled to commence or maintain any action upon any such dispute or difference until such matter shall have been referred or determined as hereinbefore provided, and then only for the amount of relief to which the Arbitrator, Arbitrators or Umpire by his or their award finds either party is entitled, and the costs of the submission, reference and award shall be in the discretion of the said Arbitrator, Arbitrators or Umpire.

¹⁾ [1997] 42 NSWLR 285