The authority of labor arbitrators to fashion and administer discovery procedures is now firmly established. The basic objective of arbitral discovery is to achieve full disclosure while avoiding the legal complexities of discovery as practiced by “litigators.” A duty of full disclosure applies to the parties. This article addresses burden of proof responsibilities (and distinguished burden-of-proof concepts in litigation); precedent, in the forms of res judicata and stare decisis; time limits set for completion of the steps in the grievance process; and whether the trier’s role should be active or passive.