In a recent decision, the Supreme Court of Nova Scotia quashed an arbitrator’s decision concerning employees’ entitlement to vacation leave in the collective agreement between the Public Service Alliance of Canada (“PSAC”) and Sydney Airport Authority. At issue before the arbitrator was whether the agreement provided that employees on ‘sick leave with pay’ continued to accrue vacation credits. The arbitrator found they did not. PSAC challenged this decision and the reviewing court concluded that the arbitrator’s award was unreasonable. The Court explained that the arbitrator failed to undertake a fulsome analysis of the intentions of the parties within the four corners of the agreement and apply the necessary interpretive principles.