For many years, labour arbitrators have interpreted management rights clauses in a purposive rather than a literal manner. This means that most arbitrators have interpreted collective agreements as implicitly authorizing only ‘reasonable’ management action. As one aspect of this approach, arbitrators long ago devised the KVP test to determine when unilateral employer rules or policies are enforceable by discipline. The KVP test is not new; but the Supreme Court has breathed new life into it. Enterprising unions will look for opportunities to apply the KVP test for their members’ benefit.