HL 2 May 1998. The employers (X) entered into a contract with the contractors (Y) using JCT 1980. Following disputes over the progress of the work Y commenced proceedings claiming payment for work in repsect of architect`s interim certificates. X denied liability and alleged that they were entitled to set off an amount in excess of that claimed by Y. Y served a notice to appoint an arbitrator. X issued a writ against Y and the architects claiming damage for negligence and breach of contract. The judge and CA in Northern Ireland dismissed appeals by X on the grounds that the court did not have the power conferred upon an arbitrator by the arbitration clause to open up, review and revise cerificates by the architect. The HL allowed an appeal by X as the court did not have the power conferred upon an arbitrator by the arbitration clause to oepn up and revise certificates by the archtiect. The HL allowed an appeal by X as they did not need to spell out the arbitrators powers.