In AT & T Technologies, Inc. v. Communications Workers of Am., 475 U.S. 643, 648, 106 S.Ct. 1415, 1418, 89 L.Ed.2d 648 (1986), a Supreme Court case on "who decides arbitrability," the "arbitrability" issue was whether the subject matter of the underlying dispute was expressly made non-arbitrable by the terms of the arbitration agreement. The arbitration clause of the collective bargaining agreement ("CBA") in AT & T expressly did not cover disputes "excluded from arbitration by other provisions of this contract." AT & T, 475 U.S. at 645, 106 S.Ct. at 1415. The CBA provided further that the employer, AT & T, was free to exercise certain management functions, including the termination of employment, "not subject to the provisions of the arbitration clause." Id. Another CBA term provided that layoffs would occur in reverse order of seniority, defining layoffs as terminations resulting from "lack of work"; the "layoff" provision did not specify whether it was subject to, or excepted from, the arbitration clause. Id. The issue was whether the union could compel arbitration over certain layoffs, or, instead, whether the layoffs were non-arbitrable management functions. The Supreme Court held that the issue whether "layoffs" were an arbitrable subject matter was to be decided by the courts, not the arbitrator, given that the parties had expressly agreed that certain subjects, including "termination of employment," were not arbitrable. Id. at 651, 106 S.Ct. at 1415. In AT & T Technologies, Inc. v. Communications Workers of America, 475 U.S. 643, 106 S.Ct. 1415, 89 L.Ed.2d 648 (1986), addressing the question of whether grievances relating to lay-offs that were prompted by reasons other than lack of work were to be arbitrated, the Supreme Court stated: It is the court's duty to interpret the agreement and to determine whether the parties intended to arbitrate grievances concerning layoffs predicated on a "lack of work" determination by the Company. If the court determines that the agreement so provides, then it is for the arbitrator to determine the relative merits of the parties' substantive interpretations of the agreement. It was for the court, not the arbitrator, to decide in the first instance whether the dispute was to be resolved through arbitration. (475 U.S. at 651, 106 S.Ct. at 1419.) In AT&T Technologies, Inc. v. Communications Workers of America, 475 U.S. 643 , 648 (1986), the Supreme Court explained that presumption favoring arbitrability in the context of a labor dispute: Finally, it has been established that where the contract contains an arbitration clause, there is a presumption of arbitrability in the sense that "an order to arbitrate the particular grievance should not be denied unless it may be said with positive assurance that the arbitration clause is not susceptible of an interpretation that covers the asserted dispute. Doubts should be resolved in favor of coverage." (475 U.S. at 650.) In AT & T Technologies v. Communication Workers, 475 U.S. 643, 106 S.Ct. 1415, 89 L.Ed.2d 648 (1986), the Supreme Court identified several factors that should be considered in determining whether a duty to arbitrate exists. First, arbitration is a matter of contract and a litigant cannot be required to submit any dispute to arbitration which he or she has not agreed to submit. Id. 475 U.S. at 648, 106 S.Ct. at 1418. Second, whether there is a duty to arbitrate a given dispute is a question for the court and not the arbitrator. Id. at 649, 106 S.Ct. at 1418. Third, in deciding whether the parties have agreed to submit a dispute to arbitration, the court is not to rule on the potential merits of the underlying claim. Id. Finally, where there is a contractual arbitration clause, there is a presumption of arbitrability, meaning that arbitration "should not be denied unless it may be said with positive assurance that the arbitration clause is not susceptible of an interpretation that covers the asserted dispute." Id. at 650, 106 S.Ct. at 1419.