of all issues to the arbitrator, including issues regarding arbitrability. Labor arbitration Arbitration may be used as a means of resolving labor disputes, an alternative to strikes and lockouts. Labor arbitration comes in two varieties: interest arbitration, which provides a method for resolving disputes about the terms to be included in a new contract when the parties are unable to agree, and grievance arbitration, which provides a method for resolving disputes over the interpretation and application of a collective bargaining agreement. Arbitration has also been used as a means of resolving labor disputes for more than a century. Labor organizations in the United States, such as the National Labor Union, called for arbitration as early as 1866 as an alternative to strikes to resolve disputes over the wages, benefits and other rights that workers would enjoy. Interest arbitration Governments have relied on arbitration to resolve particularly large labor disputes, such as the Coal Strike of 1902. This type of arbitration, wherein a neutral arbitrator decides the terms of the collective bargaining agreement, is commonly known as interest arbitration. The United Steelworkers of America adopted an elaborate form of interest arbitration, known as the Experimental Negotiating Agreement, in the 1970s as a means of avoiding the long and costly strikes that had made the industry vulnerable to foreign competition. Major League Baseball uses a variant of interest arbitration, in which an arbitrator chooses between the two sides' final offers, to set the terms for contracts for players who are not eligible for free agency. Interest arbitration is now most frequently used by public employees who have no right to strike (for example, law enforcement and firefighters). Grievance arbitration Unions and employers have also employed arbitration to resolve employee and union grievances arising under a collective bargaining agreement. The Amalgamated Clothing Workers of America made arbitration a central element of the Protocol of Peace it negotiated with garment manufacturers in the second decade of the twentieth century. Grievance arbitration became even more popular during World War II, when most unions had adopted a no-strike pledge. The War Labor Board, which attempted to mediate disputes over contract terms, pressed for inclusion of grievance arbitration in collective bargaining agreements. The Supreme Court subsequently made labor arbitration a key aspect of federal labor policy in three cases which came to be known as the Steelworkers' Trilogy. The Court held that grievance arbitration was a preferred