Public employers' challenge to arbitrators' authority is examined; management's arguments on the issue are divided into four categories: (1) substantive and procedural arbitrability, (2) reserved managerial prerogatives, (3) controlling external law, and (4) limitations on remedial power. Attention focuses on the sources of the power issue; the possibility that public management may see the power issue as a 'winner' argument is suggested. However, this argument is shown to fail to account for the greater frequency of the power issue in public sector cases; reasons for this greater frequency are considered. One explanation suggested is that the typical public sector arbitration clause is drawn more narrowly that the typical private sector arbitration clause, giving public management a firmer foundation upon which to construct its substantive arbitrability argument. Similarly, public sector collective bargaining agreements are shown to contain managerial prerogatives couched in plenary language that can support legitimate arguments based on reserved power. Three scenarios illustrate the difference between public sector collective bargaining, a political process; and adjudicatory decisionmaking by grievance arbitrators, a distinctively apolitical process. Finally, the impact of the power issue is considered, and the need for grievance arbitration to be tailored to the resolution of disputes between the government and a union representing public workers is identified. Included are 89 references.