After examining existing and proposed MLB drug testing policies, this article reviews the labor law issues raised by these policies, with attention to relevant arbitration decisions. The operation of professional sports leagues is governed under labor laws, since collective bargaining agreements have been negotiated between management and the unions. Most of the issues and cases involving drug testing and usage in MLB have been and will be resolved in the internal grievance and arbitration system as provided for in the collective bargaining agreement. In the foreseeable future, there will probably be a stalemate over mandatory drug testing in MLB, given a 1986 arbitration decision and the Players Association's refusal to agree to any mandatory plan. The arbitration decision by Thomas Roberts held that drug testing clauses of the collective bargaining agreement must be negotiated with the Players Association. 176 footnotes.