An arbitrator cannot act outside the scope of his reference, the Allahabad High Court ruled on January 12 holding that arbitration under section 3-G (5) of The National Highways Act, 1956 is limited to the determination of the fair amount of compensation, and is not a proceeding to judge the correctness of the compensation determined by the competent authority (Bhartiya Rashtriya Rajmarg Pradhikaran vs Rajesh Kaushik).